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DigInterface
Free DNS, Email & Developer Tools
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Step-by-step guides for every tool on DigInterface. Click a tool name to jump to its guide.

🔍

DNS Lookup Tool

Open Tool →

Steps

  1. Enter one or more domain names in the text area, one per line. For example: google.com or multiple like google.com and microsoft.com on separate lines.

  2. Select the record types you want to query from the dropdown. Choose individual types (A, MX, TXT, SPF, DKIM, DMARC, etc.) or select All to query every supported type at once.

  3. Choose a DNS resolver — Google (8.8.8.8), Cloudflare (1.1.1.1), OpenDNS or Quad9. Google is selected by default and works well for most queries.

  4. For DKIM lookups, select DKIM as the record type and a selector field will appear. Enter the selector name — for example google, s1 or default. Check the email headers of a message from the domain to find the selector (look for s= in the DKIM-Signature header).

  5. Optionally tick Include Security Check to also check DNSSEC, MTA-STS, BIMI, DANE, MX, NS and CAA configuration.

  6. Click Lookup. Results appear colour-coded — green for successful records, yellow for missing records, red for errors.

  7. Use the Download TXT or Download CSV buttons to export results for reporting or documentation.

Practical Tips

  • Query the same domain on different resolvers (Google vs Cloudflare) to check for propagation issues — if results differ, DNS changes are still propagating.
  • When troubleshooting email delivery, start with MX, SPF, DKIM and DMARC all at once using the multi-select dropdown.
  • The SOA record shows the primary nameserver and the serial number — a useful way to confirm whether a DNS change has been picked up by a specific resolver.
  • PTR records require you to enter the reverse DNS notation — for example 1.0.0.127.in-addr.arpa for IP 127.0.0.1. Most hosting panels let you set PTR records directly.

Common Use Cases

  • Verifying MX records point to the correct mail server after a migration
  • Checking SPF, DKIM and DMARC are correctly published before go-live
  • Confirming DNS propagation after changing nameservers or A records
  • Auditing multiple domains at once for missing email security records
  • Looking up TXT records for domain verification tokens (Google, Microsoft, etc.)
🚫

Blacklist Checker

Open Tool →

Steps

  1. Enter an IP address or domain name in the input field. You can enter an IPv4 address (e.g. 203.0.113.10), an IPv6 address, or a domain name (e.g. yourdomain.com).

  2. Click Check Blacklists. The tool checks all lists in parallel — this usually takes 5–10 seconds.

  3. Review the summary badge at the top of the results — it shows how many lists you are listed on out of the total checked. Green means clean, red means at least one listing was found.

  4. If you entered a domain, two tables appear: IP-Based Blacklists (for the domain's resolved IP) and Domain-Based Blacklists (for the domain itself). Results are sorted with any listings at the top.

  5. For any listing, check the Reason column — this shows the TXT record explanation provided by that blacklist. Click Lookup to open the blacklist's own page for that IP or domain, which usually includes removal instructions.

  6. Download results as TXT or CSV for documentation or reporting to management.

Practical Tips

  • Always check the domain name rather than just the IP — some blacklists (like Spamhaus DBL) list domains specifically and a clean IP does not mean the domain is clean.
  • If you are listed on UCEPROTECT L2 or L3 only, this often means your ISP or hosting provider's IP range is listed rather than your specific IP — investigate whether the listing applies to your IP individually.
  • Spamhaus ZEN is the most critical list — it is queried by most major mail providers. Prioritise delisting from ZEN above all others.
  • Run the check again 24–48 hours after fixing the underlying issue to confirm delisting has taken effect.

Common Use Cases

  • Diagnosing why outbound emails are being rejected or going to spam
  • Checking a new sending IP before onboarding it to a mail platform
  • Routine monitoring of your mail server IP reputation
  • Verifying a third-party sender's IP reputation before allowing them to send on your behalf
  • Checking whether a domain you received spam from is already listed
📧

Email Header Analyzer

Open Tool →

How to Get Raw Email Headers

  1. Gmail: Open the email, click the three-dot menu (⋮) in the top right of the message and select Show original. Copy everything in the box that appears.

  2. Outlook (desktop): Open the email, go to File → Properties and copy the contents of the Internet headers box.

  3. Outlook (web): Open the email, click the three-dot menu → View → View message source. Copy the header section at the top.

  4. Apple Mail: Select the email and go to View → Message → All Headers.

Analysing the Results

  1. Paste the raw headers into the text area and click Analyze Headers.

  2. Check the Authentication Results section first. Each of SPF, DKIM, DMARC and ARC will show as pass (green), fail (red) or none (yellow). Any fail or none is a potential cause of spam classification.

  3. Review the Relay Information section. Hops are shown in chronological order (first hop at the top). Check the delay column — a hop with a very large delay (30+ seconds) indicates a slow or problematic mail server in the delivery chain.

  4. Scroll down to the Parsed Headers table for a complete breakdown of every header field — useful for inspecting X-headers, Message-ID, Content-Type and other fields.

Practical Tips

  • If DKIM shows fail but SPF passes, check whether the email was forwarded — forwarding breaks DKIM alignment because the message body is often modified.
  • A DMARC fail despite SPF or DKIM passing usually means the From domain does not align with the authenticated domain — check your DMARC policy and alignment mode.
  • The first Received header (at the top of the stack in the raw headers) is added by your receiving mail server and is the most trustworthy — work backwards from there to trace the origin.
  • Look for X-Spam-Score or X-Spam-Status headers from the receiving server — these show what spam score the message was assigned and why.

Common Use Cases

  • Diagnosing why legitimate emails are landing in spam
  • Verifying SPF, DKIM and DMARC are passing end-to-end after configuration
  • Tracing the origin of a suspicious or phishing email
  • Identifying delivery delays in the mail relay chain
  • Troubleshooting email authentication failures for a specific sender
🌐

WHOIS Lookup

Open Tool →

Steps

  1. Enter a domain name or IP address in the search field. Examples: example.com, 8.8.8.8, or an IPv6 address like 2001:4860:4860::8888.

  2. Click Lookup. A loading spinner indicates the query is running — IP WHOIS lookups via RDAP may take a few seconds.

  3. For domain lookups, review the Domain Registration Details card which shows registrar, registration date, expiry date, nameservers, status flags and DNSSEC information.

  4. For IP lookups, three expandable sections appear: ASN Information (autonomous system number, CIDR range, registry and country), Network Information (network name, IP range, type and events) and Entity / Contact Details (contact handles, organisation, addresses, emails and roles).

  5. Click the Copy All button to copy the full result to your clipboard, or use Download TXT / CSV to save the data.

Practical Tips

  • Domain expiry date is shown in the registration details — if a domain you rely on is expiring soon, flag it for renewal immediately.
  • The ASN CIDR field shows the entire IP range allocated to that autonomous system — useful for understanding the scope of a sender's IP allocation.
  • Status flags like clientTransferProhibited are normal and mean the domain is locked against unauthorised transfers. If you see serverHold or redemptionPeriod the domain may be suspended or about to expire.
  • For abuse reporting, the Entity section lists the abuse contact role and email address for the IP's network owner.

Common Use Cases

  • Identifying who owns an IP that is sending spam or making suspicious connections
  • Checking domain registration and expiry dates
  • Finding the correct abuse contact to report malicious traffic
  • Verifying nameservers are pointing to the correct registrar or DNS provider
  • Researching the network ownership behind a domain or IP during an incident
⚙️

SPF Macro Tester

Open Tool →

Steps

  1. Enter the SPF macro string you want to test. This is typically the macro portion of an SPF exists: or include: mechanism, for example: %{i}._spf.%{d} or a full SPF include domain like spf.protection.outlook.com.

  2. Enter the Sender IP — the IP address of the mail server that would be sending the email. This populates the %{i} and %{c} macros.

  3. Enter the HELO/EHLO hostname — the hostname the sending server announces in the SMTP HELO or EHLO command. This populates the %{h} macro.

  4. Enter the Sender Email — the envelope From address (MAIL FROM). This populates %{s} (full address), %{l} (local part) and %{o} (domain part) macros.

  5. Enter the Envelope Domain — usually the domain part of the sender email. This populates the %{d} macro.

  6. Click Expand Macro. The tool shows the fully expanded macro string, performs a live DNS TXT lookup on the result and runs a full SPF check showing the final result (pass, fail, softfail, etc.).

Practical Tips

  • Common macros: %{i} = sender IP, %{s} = full sender email, %{d} = envelope domain, %{h} = HELO hostname, %{l} = local part of sender email, %{o} = sender domain.
  • If an SPF record uses exists:%{i}._spf.example.com, the tool will expand and resolve each exists macro individually so you can see exactly which IP ranges are being whitelisted.
  • Use this tool before deploying a new SPF record that includes macros — test it with a real sending IP to confirm it expands correctly and returns the expected result.
  • A softfail result (~all) means the IP is not authorised but the receiving server may still accept the message. A hardfail (-all) means it should be rejected.

Common Use Cases

  • Debugging why SPF is failing for a specific sending IP
  • Testing SPF exists mechanisms used by services like Mimecast or Proofpoint
  • Verifying SPF macro expansion before publishing a new SPF record
  • Understanding what a third-party SPF include resolves to for a given sender
🔤

Regex Tester

Open Tool →

Steps

  1. Select the regex engine from the flavour dropdown: Python (re) for standard Python regex, PCRE for advanced patterns with atomic groups and \K, or ECMAScript for JavaScript-style regex evaluated live in the browser.

  2. Set any flags you need using the checkboxes: Ignore Case makes matching case-insensitive, Multiline makes ^ and $ match line boundaries, Dot Matches Newline makes . match any character including newlines.

  3. Enter your regex pattern in the Pattern field. You do not need to wrap it in slashes — just enter the pattern itself, for example \b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}\b.

  4. Enter the test text in the large text area — this is the string the regex will be run against.

  5. Results update live as you type. Matches are highlighted in green in the test text, and each match is listed below with its start position, end position and any named capture groups.

Practical Tips

  • Use named capture groups for cleaner output — in Python/PCRE use (?P<name>...), in ECMAScript use (?<name>...). The group names and matched values appear in the results table.
  • The Multiline flag is essential when testing patterns against log files or multi-line text where you want ^ and $ to match each line rather than the entire string.
  • If you are writing a regex for use in Python code, use the Python (re) engine. If it is for a JavaScript application, use ECMAScript — the browser evaluates it directly so behaviour is identical to what you will get in production.
  • Test with edge cases — paste in examples that should NOT match as well as examples that should, to confirm the pattern is specific enough.

Common Use Cases

  • Building and testing email address or IP address validation patterns
  • Extracting fields from log file lines before writing a parser
  • Testing URL pattern matching rules for web application firewalls
  • Writing patterns for Mimecast or other email gateway policy rules
  • Validating regex syntax before deploying to production code
📂

HAR & JSON Viewer

Open Tool →

How to Export a HAR File

  1. Chrome / Edge: Open DevTools with F12, go to the Network tab, tick Preserve log, reproduce the issue, then right-click any request and select Save all as HAR with content.

  2. Firefox: Open DevTools with F12, go to the Network tab, reproduce the issue, click the gear icon and choose Save all as HAR.

  3. Safari: Enable the Develop menu (Preferences → Advanced), open Web Inspector, go to the Network tab, reproduce the issue, then click Export.

Using the Viewer

  1. Upload the .har or .json file by dragging it onto the drop zone, clicking to browse, or switching to the Paste tab to paste content directly.

  2. For HAR files, the waterfall chart loads automatically showing all requests in chronological order with colour-coded timing bars. The summary cards at the top show total requests, transferred bytes, total time and error count.

  3. Filter the waterfall by typing in the URL filter box, selecting a status code range (2xx, 3xx, 4xx, 5xx) or clicking the content type badges to show/hide specific resource types.

  4. Click any row to open the detail panel showing request and response headers, request body, response body, cookies and a per-phase timing breakdown.

  5. Switch to JSON Tree view to explore the raw HAR structure or any JSON file in a collapsible tree with syntax highlighting. Use the search box to find specific keys or values. Switch to Raw view to copy or download the formatted JSON.

Practical Tips

  • The waterfall bar colour key: red = Blocked, green = DNS, orange = Connect, purple = TLS, blue = Send, teal = Wait (TTFB), light green = Receive. A long teal bar means the server is slow to respond; a long orange/purple bar suggests a connection or TLS handshake issue.
  • Filter by 4xx or 5xx status to quickly isolate failed requests in a large HAR file with hundreds of entries.
  • HAR files can contain sensitive data including auth tokens, session cookies and API keys — the viewer processes everything in your browser so nothing is sent externally, but be careful sharing HAR files with others.
  • Use the JSON Tree view with the search function to find a specific header, cookie name or response field buried deep in the HAR structure.

Common Use Cases

  • Diagnosing slow page loads by identifying which requests take the most time
  • Debugging API calls — inspecting request bodies, response codes and response payloads
  • Investigating failed authentication flows by checking redirect chains and cookie values
  • Sharing network traces with a support team in a readable format
  • Exploring any JSON API response in a human-readable tree view
🕐

Timestamp Converter

Open Tool →

Steps

  1. The live clock at the top shows the current Unix timestamp updating every second — useful as a quick reference without needing to type anything.

  2. To convert a Unix timestamp: paste the number into the Unix Timestamp panel. The tool auto-detects whether it is in seconds (10 digits), milliseconds (13 digits), microseconds (16 digits) or nanoseconds (19 digits) and instantly shows all equivalent formats.

  3. To convert an ISO 8601 date: paste a date like 2025-04-22T10:30:00.000Z or 2025-04-22T20:30:00+10:00 into the ISO 8601 panel.

  4. To convert a specific UTC date and time: use the date and time pickers in the UTC panel. The second field is separate so you can set precise values including seconds.

  5. To convert your local time: use the Your Time Zone panel — it uses your browser's local timezone automatically.

  6. Click Load Current Time to populate all four panels with the current time simultaneously — useful when you need the current timestamp in multiple formats at once.

Practical Tips

  • JavaScript timestamps are always in milliseconds (13 digits). If you are reading a timestamp from a JavaScript application or browser log, paste it directly — the tool handles it automatically.
  • The Quick Reference table at the bottom shows the current time, Unix epoch (0), +1 hour, +1 day, +1 week, Y2K and the Y2K38 problem timestamp — handy for quick calculations.
  • When comparing timestamps from different systems, always convert to UTC first to avoid timezone confusion. The tool always shows the UTC equivalent alongside local time.
  • ISO 8601 with a timezone offset (e.g. +10:00) is handled correctly — the tool converts to UTC before calculating the Unix timestamp.

Common Use Cases

  • Converting log file timestamps to human-readable dates for incident investigation
  • Comparing event timestamps from different systems that use different formats
  • Generating the current Unix timestamp for use in API calls or scripts
  • Converting a specific date and time to Unix format for database queries
  • Quickly checking what a timestamp in a JWT token or API response represents
🖥

Live HTML Editor

Open Tool →

Steps

  1. Start with a snippet if you are building something from scratch — click the Snippets menu and choose a template like HTML5 Page for a general page or Email Template for an HTML email.

  2. Edit the HTML in the left pane. The preview on the right updates automatically as you type. Press Ctrl+Space to trigger HTML autocomplete at any point.

  3. Use code folding by clicking the arrow in the gutter next to any opening tag — useful for collapsing sections you are not currently editing in longer documents.

  4. Click Format (✨) to automatically clean up indentation and make the code easier to read.

  5. Use the preview size toggle to check how your HTML looks at desktop (full width), tablet (768px) or mobile (375px) — important for responsive layouts and email templates.

  6. When finished, click Copy to copy the HTML to your clipboard, or Download to save it as index.html.

Keyboard Shortcuts

  • Ctrl+Space — trigger HTML autocomplete at the cursor position.
  • Ctrl+/ — toggle comment on the current line or selection.
  • Ctrl+Q — fold or unfold the code block at the cursor.
  • Tab — indent selected lines or insert 4 spaces at the cursor.
  • Auto-close tags — type <div> and the closing </div> is inserted automatically.

Practical Tips

  • The Email Template snippet uses table-based layout for maximum email client compatibility — keep it table-based if you are building HTML emails for Outlook or other older clients.
  • Use the mobile preview to test email templates before sending — most email is now read on mobile and a template that looks good on desktop can break badly on a 375px screen.
  • The Open Graph Tags snippet gives you the meta tags needed for rich previews when your page is shared on social media or in messaging apps.
  • Disable auto-refresh for very large HTML files to avoid constant re-rendering while you type — then click Run manually when ready to preview.

Common Use Cases

  • Quickly prototyping an HTML email template before building it in a mail platform
  • Testing a snippet of HTML from a CMS or template engine
  • Building and previewing a simple standalone HTML page
  • Learning HTML with instant visual feedback as you type
  • Generating and previewing Open Graph or meta tag markup
📤

SMTP Send & Open Relay Test

Open Tool →

Sending a Test Email

  1. Log in with your DigInterface account. If you do not have one, register for free — email verification is required before you can use this tool.

  2. Make sure SMTP Send mode is selected (the default). Enter the SMTP server hostname and port — common ports are 25 (unauthenticated), 587 (STARTTLS) and 465 (TLS).

  3. Choose the connection type: Plain (no encryption), STARTTLS (recommended for port 587) or TLS (for port 465).

  4. Enter the Envelope From (MAIL FROM address) and Header From (the From address shown to the recipient). Leave Envelope From blank to send as <> (null sender — used for bounce notifications).

  5. Enter the Recipient Email, Subject and Body. Optionally attach a file.

  6. Enter SMTP username and password if the server requires authentication. Leave blank for unauthenticated tests.

  7. Tick Enable Verbose Logging to see the full SMTP conversation in the transmission log. Complete the CAPTCHA and click Send Email.

Running an Open Relay Test

  1. Click the Open Relay Test button to switch modes.

  2. Enter the Target SMTP Host — the hostname or IP of the server you want to test. This connects directly to the host, bypassing MX lookup.

  3. Enter a Recipient Email at a domain the target server does not host — for example a Gmail address. If the server accepts and delivers the message it is likely an open relay.

  4. Select port 25 or 587 and a connection type, complete the CAPTCHA and click Run Open Relay Test.

  5. Review the transmission log — if the server returns 250 OK after the DATA command and the email is delivered, the server is an open relay. If it returns a 550 or 554 rejection it is correctly configured.

Practical Tips

  • The Envelope From and Header From can be different — this is normal in legitimate email (e.g. bulk senders often use a bounce address as the envelope from). Use this to test how a receiving server handles mismatches.
  • A null sender (<>) as the Envelope From is used for delivery status notifications and bounce messages — useful for testing whether a receiving server correctly accepts DSNs.
  • Verbose mode is essential for diagnosing connection failures — it shows exactly which SMTP command the server rejected and what error code it returned.
  • Open relay tests send a DKIM-signed message from smtptest.diginterface.com so the test email itself is legitimate and should not trigger spam filters based on the sender.

Common Use Cases

  • Testing that a new SMTP relay server accepts authenticated connections correctly
  • Verifying STARTTLS is working on a mail server before go-live
  • Diagnosing why emails from a specific server are being rejected
  • Testing open relay configuration on a mail server after hardening
  • Sending test messages with controlled envelope and header From values to test gateway policies
🔒

SSL/TLS Certificate Checker

Open Tool →

Steps

  1. Enter the domain name you want to check — for example www.example.com. Do not include https://.

  2. Set the port if it is not the standard 443. Common alternatives are 8443 (alternative HTTPS), 465 (SMTPS), 993 (IMAPS) and 636 (LDAPS). Leave as 443 for standard websites.

  3. Click Check Certificate. The tool connects directly to the host, retrieves the certificate chain and displays the results.

  4. Check the status pills at the top — green means valid, yellow means expiring within 30 days, red means expired or a hostname/chain issue.

  5. Review Certificate Details for the issuer, serial number, signature algorithm, key type and exact validity dates with a countdown bar.

  6. Check the Subject Alternative Names list to see all domains covered by the certificate — wildcard entries like *.example.com will appear here.

  7. Review the Protocol & Cipher section to confirm the negotiated TLS version (TLS 1.3 is ideal) and cipher suite.

Practical Tips

  • Check certificates proactively — don't wait for users to report browser warnings. A 30-day warning gives you time to renew without disruption.
  • If the hostname doesn't match, check whether the certificate covers a wildcard or a different subdomain — the SAN list shows all covered domains.
  • TLS 1.3 is the current best practice. If the tool shows TLS 1.2 as the negotiated version, check whether TLS 1.3 is enabled on the server.
  • The expiry progress bar shows how much of the certificate's total lifetime has been used — a certificate near the end of its life needs renewal soon regardless of days remaining.

Common Use Cases

  • Verifying a newly installed certificate is valid and covers the correct domain
  • Checking certificate expiry dates before a maintenance window
  • Confirming TLS version and cipher suite after a server hardening change
  • Checking which SANs are covered by a wildcard certificate
  • Diagnosing "certificate not trusted" browser warnings
🌍

DNS Propagation Checker

Open Tool →

Steps

  1. Enter the domain name you want to check propagation for — for example example.com or mail.example.com.

  2. Select the record type from the dropdown — choose the specific record type you just changed: A for IP changes, MX for mail server changes, TXT for SPF/DMARC/verification records, NS for nameserver changes, etc.

  3. Click Check Propagation. The tool queries 20 resolvers simultaneously — this takes a few seconds.

  4. Review the summary bar at the top showing how many resolvers have the new answer, how many still have the old one, and the overall propagation percentage.

  5. The Most Common Answer box shows the consensus — what the majority of resolvers are returning. This is usually the new record once propagation is mostly complete.

  6. Resolvers marked ✓ Propagated (green) are returning the consensus answer. Those marked ✗ Different (red) are still returning a different answer — usually the old record.

  7. Reload the page to re-run the check and see updated propagation status — there is no auto-refresh.

Practical Tips

  • Before making a DNS change, lower the TTL of the record to 300 seconds (5 minutes) and wait for the current TTL to expire. Then make your change — it will propagate much faster.
  • If the propagation percentage is stuck below 100% for more than a few TTL cycles, check that the change was actually saved at your registrar or DNS provider.
  • Different resolvers showing different answers is normal during propagation — it just means some caches haven't expired yet.
  • For MX record changes, use the propagation checker to confirm all resolvers have the new MX before switching over mail flow to avoid missed emails.

Common Use Cases

  • Confirming A record changes have propagated globally after changing hosting provider
  • Verifying MX record changes before cutting over email to a new provider
  • Checking NS record propagation after moving to a new DNS provider
  • Confirming TXT records (SPF, DMARC, verification tokens) are visible globally
  • Diagnosing intermittent DNS issues affecting some users but not others
📊

Email Deliverability Tester

Open Tool →

Steps

  1. Enter the domain name you want to test — this should be the domain used in the From address of outbound emails (e.g. yourcompany.com).

  2. Enter a DKIM selector if you want to include a DKIM check. To find your selector, open any outbound email in a mail client, view the raw headers and look for the DKIM-Signature header — the selector is the value after s=. Common selectors are google, s1, s2, default, selector1.

  3. Click Run Checks. The tool runs all checks in parallel — results appear within a few seconds.

  4. Review the score circle — 85+ is excellent, 65–84 is good, below 65 needs attention.

  5. Work through any red (fail) cards first — these are the issues most likely to cause email rejection or spam classification. Then address yellow (warn) items.

  6. Each card includes a 💡 advice line explaining what to do to fix the issue.

  7. Review the MX Records table at the bottom to confirm your mail servers are resolving correctly.

Practical Tips

  • Run this check on any new domain before sending email from it — catching missing SPF or DMARC early prevents deliverability problems from the start.
  • If SPF shows more than 10 DNS lookups, emails will fail SPF with a permerror at receiving servers. Simplify the SPF record or use SPF flattening to fix this.
  • A DMARC policy of p=none means monitoring only — it doesn't protect your domain from spoofing. Move to p=quarantine or p=reject once you've reviewed your DMARC reports.
  • Missing PTR (reverse DNS) records can cause some receiving servers to reject or score email as spam — ask your hosting provider to set up PTR records for your mail server IPs.

Common Use Cases

  • Pre-flight check before launching email from a new domain
  • Diagnosing why emails are going to spam or being rejected
  • Auditing email configuration for a domain after a migration
  • Regular health checks for customer domains as part of a TAM or support role
  • Checking a third-party sender's domain configuration before allowing them to send on your behalf
🔤

Base64 Encoder / Decoder

Open Tool →

Base64 Encode & Decode

  1. Click the Base64 Encode or Base64 Decode tab depending on what you need.

  2. Type or paste your text into the left panel. The result appears in the right panel automatically as you type.

  3. For encoding, tick URL-safe if the output will be used in a URL, JWT or filename — this replaces + with - and / with _.

  4. Tick Line-break every 76 chars if the output needs to be formatted for email (MIME standard).

  5. Use the ⇅ Swap button to instantly swap input and output — useful for round-tripping encode then decode.

  6. Click 📋 Copy to copy the output to your clipboard.

File to Base64

  1. Click the File → Base64 tab.

  2. Drag and drop any file onto the drop zone, or click to browse. Images, PDFs, fonts — any file type works.

  3. The Base64 output and a Data URI (data:image/png;base64,...) appear immediately. The Data URI can be pasted directly into an HTML src="" or CSS url() attribute to embed the file without a separate HTTP request.

JWT Decoder

  1. Click the JWT Decoder tab.

  2. Paste a JWT token (starts with eyJ) into the text area.

  3. The header, payload and signature are decoded and displayed in colour-coded panels. The claims table below shows each payload field with a plain-English explanation — including expiry time in human-readable format and a warning if the token has already expired.

  4. Note: the signature is not verified — this is a decode-only tool. Never trust a JWT's claims in a security context without verifying the signature.

Practical Tips

  • All processing happens in your browser — no data is sent to the server. Safe to use with sensitive tokens and credentials.
  • The decoder handles both standard and URL-safe Base64 automatically — you don't need to manually add padding or convert characters.
  • Use the JWT decoder to quickly check what claims a token contains and whether it has expired — useful when debugging API authentication issues.

Common Use Cases

  • Encoding API credentials or binary data for HTTP transmission
  • Decoding Base64-encoded email attachments or headers
  • Embedding small images or fonts directly in HTML using Data URIs
  • Inspecting JWT tokens from API responses to check claims and expiry
  • Encoding/decoding URL query parameters that contain special characters
🖧

Subnet & CIDR Calculator

Open Tool →

Steps

  1. Enter an IP address with CIDR notation in the input field — for example 192.168.1.0/24 or 10.0.0.0/255.255.0.0. You can also use the Quick chips below the input to load common subnets instantly.

  2. Results appear automatically as you type — no need to click Calculate unless you want to force a recalculation.

  3. Review the Network Information card for subnet mask, wildcard mask and network class.

  4. Check the Address Range card for network address, first and last usable hosts and broadcast address.

  5. The Capacity card shows total addresses and usable host count, plus whether the IP is private, public, loopback or link-local.

  6. The Binary Representation card shows the IP, mask and network address in binary with network bits highlighted in blue and host bits in green — useful for understanding how CIDR works.

  7. To split the network into subnets, change the Split into /__ subnets value in the Subnet Breakdown section. The table updates instantly showing network, first host, last host, broadcast and host count for each subnet.

Practical Tips

  • A /24 gives 254 usable hosts, /25 gives 126, /26 gives 62, /27 gives 30, /28 gives 14. Halving the prefix adds one bit and doubles the addresses.
  • The wildcard mask is the inverse of the subnet mask and is used in Cisco ACLs and some firewall rules — it shows which bits are variable (host bits).
  • Private IP ranges are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 — the IP Type field confirms whether your address falls in one of these ranges.
  • Use the subnet breakdown table to plan IP address allocation before configuring VLANs, cloud VPCs or firewall rules — it shows exactly what each subnet's range looks like before you commit.

Common Use Cases

  • Planning IP address allocation for a new network or VLAN
  • Calculating usable host ranges before configuring DHCP scopes
  • Verifying subnet boundaries when writing firewall rules or ACLs
  • Understanding how a CIDR block is divided when setting up cloud VPCs
  • Converting between subnet mask and CIDR notation