Free Security & Developer Tools
60 focused utilities for developers shipping AI-built apps. Verify one thing fast, then run a full SimplyScan for the whole picture.
- Free SSL Certificate Checker · Instantly verify a site's SSL certificate · issuer, expiration date, TLS version, and hostname match.
- Free Email Security Checker (SPF, DKIM, DMARC) · Check your domain's email authentication · SPF, DKIM, and DMARC · and see if you're vulnerable to spoofing.
- Free Security Headers Checker · Get an A-F grade on your site's HTTP security headers, including CSP, HSTS, and cross-origin isolation policies.
- Free Exposed Files Scanner · Check whether your site accidentally exposes .env, .git/config, backup archives, or other high-risk files.
- Free AI Visibility Checker (AEO) · See whether ChatGPT, Claude, Perplexity, Gemini and other AI engines can crawl and cite your site · and how to fix it if they can't.
- Free SEO Checker · Get an instant on-page SEO grade · title, meta description, indexability, structured data, Open Graph, image alt text and more.
- Free JWT Debugger & Decoder · Paste a JSON Web Token to decode its header and payload · and get flagged for alg:none, weak algorithms, missing expiry, and sensitive claims.
- Free Content Security Policy (CSP) Evaluator · Paste a Content-Security-Policy and get an A-F grade · with specific fixes for unsafe-inline, unsafe-eval, wildcards, and missing directives.
- Free Password Strength Checker · Test any password's strength · entropy, estimated crack time, and detection of common patterns and dictionary words.
- Free Hash Generator (MD5, SHA-1, SHA-256, SHA-512) · Generate MD5, SHA-1, SHA-256, SHA-384 and SHA-512 hashes from any text · instantly and entirely in your browser.
- Free Base64 Encoder & Decoder · Encode text to Base64 or decode it back · with full UTF-8 support. Handy for inspecting tokens, data URIs, and encoded config.
- Free SRI Hash Generator (Subresource Integrity) · Generate a Subresource Integrity hash for any script or stylesheet · paste the content or upload the file · so a compromised CDN can't tamper with it.
- Free DNS Security Checker (DNSSEC & CAA) · Check whether a domain is protected by DNSSEC and restricts certificate issuance with CAA records · two defenses against DNS hijacking and rogue certificates.
- Free security.txt Validator · Check whether a site publishes a valid security.txt · the RFC 9116 file that tells researchers how to responsibly report vulnerabilities.
- Free CORS Misconfiguration Tester · Test any URL for dangerous CORS misconfigurations · origin reflection, wildcard-with-credentials, and null-origin acceptance that can leak authenticated data.
- Free Password Generator · Generate strong, cryptographically random passwords · choose the length and character sets, then copy with one click.
- Free UUID Generator (v4 & v7) · Generate UUID v4 or time-ordered v7 identifiers · single or in bulk · using the browser's cryptographic random source.
- Free API Key & Secret Token Generator · Generate random API keys and secrets · hex, base64url, or alphanumeric, with an optional prefix · straight from your browser's CSPRNG.
- Free .gitignore Generator · Pick your stack and get a ready .gitignore · with the .env and secret-file rules that keep credentials out of your repository.
- Free Meta Tags Generator · Fill in your page details and get copy-ready meta tags · with a live preview of how the page will look in Google and social feeds.
- Free UTM Link Builder · Build tracking URLs with UTM parameters · validated and encoded correctly, so your analytics attribute traffic to the right campaign.
- Free URL Slug Generator · Turn any headline into a clean URL slug · lowercase, hyphenated, accent-free, with optional stop-word removal.
- Free CSP Generator (Content Security Policy Builder) · Build a Content-Security-Policy header from scratch · pick directives and sources, and get a copy-ready header with the risky options explained.
- Free Basic Auth Header Generator · Turn a username and password into a ready Authorization: Basic header · encoded locally, never transmitted.
- Free HMAC Generator (SHA-256 / SHA-512) · Compute an HMAC signature from a message and secret key · SHA-256/384/512, hex or Base64 output, all in your browser via Web Crypto.
- Free PKCE Code Verifier & Challenge Generator · Generate a spec-compliant PKCE pair · a random code_verifier and its SHA-256 code_challenge · for testing OAuth 2.0 authorization-code flows.
- Free JWT Generator (HS256) · Build a signed HS256 JSON Web Token for testing · edit the payload, set a secret, and copy the token. Everything runs locally via Web Crypto.
- Free TOTP Code Generator (2FA One-Time Passwords) · Turn a Base32 secret or otpauth:// URI into live two-factor codes · the same math your authenticator app runs, right in your browser.
- Free Data URI Generator (File to Base64) · Convert a file or image into a Base64 data URI · ready to inline into HTML, CSS, or JSON. The file is read locally and never uploaded.
- Free URL Encoder & Decoder · Encode or decode percent-encoded URLs · with separate modes for full URLs and individual query components.
- Free HTML Entity Encoder & Decoder · Escape special characters to HTML entities · or decode &-style entities back to readable text.
- Free JSON Formatter & Validator · Paste JSON to pretty-print, minify, or validate it · with the exact line and position of any syntax error.
- Free JSON to TypeScript Converter · Convert a JSON payload into TypeScript interfaces · nested objects and arrays included · ready to paste into your codebase.
- Free CSV to JSON Converter · Convert between CSV and JSON in either direction · with proper handling of quoted fields, commas inside values, and headers.
- Free Unix Timestamp Converter · Convert Unix epoch timestamps to readable dates and back · seconds and milliseconds auto-detected, UTC and local shown together.
- Free Case Converter (camelCase, snake_case, kebab-case) · Paste any identifier or phrase and get every casing variant at once · camelCase, snake_case, kebab-case, PascalCase, CONSTANT_CASE and more.
- Free Number Base Converter (Binary, Hex, Octal, Decimal) · Type a number in any base · binary, octal, decimal, or hex · and see it converted to all the others instantly.
- Free cURL to fetch Converter · Paste a curl command · from API docs or your terminal · and get clean JavaScript fetch code with headers and body intact.
- Free Markdown to HTML Converter · Write or paste Markdown and get clean HTML plus a live preview · headings, lists, links, code blocks, and tables included.
- Free Color Converter (HEX, RGB, HSL) · Convert any color between HEX, RGB, and HSL · type in one format and get the others, with a live swatch and CSS-ready values.
- Free Text Diff Checker · Paste two versions of a text or file and see exactly what changed · line-by-line, with additions and removals highlighted.
- Free Regex Tester (JavaScript) · Write a pattern, paste test text, and see matches highlighted live · with capture groups, flags, and match positions.
- Free Cron Expression Parser & Explainer · Paste any cron expression and get a plain-English schedule plus the next five run times · no more guessing what */15 2,14 * * 1-5 means.
- Free .env File Security Linter · Paste your .env and get instant findings · secrets that will ship to the browser, duplicate keys, quoting problems · plus a generated .env.example.
- Free Secret Scanner · Find API Keys in Code · Paste any code, config, or bundle excerpt and get flagged secrets · AWS keys, Stripe live keys, OpenAI keys, GitHub tokens, JWTs, private key blocks and more.
- Free URL Parser & Query String Viewer · Paste any URL and see every part broken out · protocol, host, path, and each query parameter decoded into a readable table.
- Free User-Agent Parser · Paste a User-Agent string · from logs or analytics · and identify the browser, OS, device class, and whether it's a known bot or AI crawler.
- Free Email Header Analyzer · Paste raw email headers and get the story: did SPF, DKIM and DMARC pass, what path did the message take, and does anything look spoofed.
- Free CIDR Subnet Calculator · Enter CIDR notation like 10.0.0.0/24 and get the full picture · network, broadcast, usable range, mask, and how many hosts fit.
- Free Color Contrast Checker (WCAG) · Pick a text and background color and get the WCAG contrast ratio · with pass/fail for AA and AAA at normal and large text sizes.
- Free robots.txt Tester & Validator · Paste your robots.txt and test any URL against it · per user-agent, including AI crawlers · using the same longest-match rules Google applies.
- Free Semver Range Checker · Enter a version range like ^4.2.0 and a version to test · see whether it matches and what the range actually allows.
- Free MIME Type Lookup · Search by file extension or MIME type · get the correct Content-Type for serving any file, with notes on the security-sensitive ones.
- HTTP Status Codes Reference · Every HTTP status code, searchable · what each means, when to use it, and which ones have security implications worth knowing.
- Free chmod Calculator · Toggle read/write/execute for owner, group, and others · and get the octal and symbolic chmod notation both ways.
- Free Punycode / IDN Converter · Convert Unicode domains to xn-- punycode and back · and check whether a domain mixes scripts the way phishing lookalikes do.
- Free DNS Lookup (A, AAAA, MX, TXT, NS, CNAME) · Query any domain's DNS records live · A, AAAA, CNAME, MX, TXT, NS, and CAA · resolved over encrypted DNS-over-HTTPS.
- Free AES Text Encryption (AES-256-GCM) · Encrypt text with a password using AES-256-GCM · and decrypt it back. Keys are derived with PBKDF2 and everything stays in your browser.
- Common Port Numbers Reference · Search any port number or service · see what normally runs there and whether it belongs on the public internet.
- Free XML Formatter & Validator · Paste XML · a sitemap, RSS feed, SVG, or API response · and pretty-print, minify, or validate it instantly.