Free Developer Tools

Format and validate data, test regular expressions, decode tokens, generate IDs and hashes, and check DNS and email headers. Inputs stay in your browser tab, which matters when you paste tokens or keys.

All 27 tools here work now, and none of them needs credits.

JSON FormatterValidate, pretty-print and minify JSON privately.Regex TesterTest JavaScript regular expressions: matches highlighted, capture and named groups, flags, replace and common patterns.JWT DecoderDecode a JWT's header and claims, check expiry, and verify the signature with a secret or public key.JWT GeneratorCreate signed JSON Web Tokens for testing: HS256 with a secret, or RS256, ES256 and EdDSA with a key pair.Base64 Encoder / DecoderEncode text, images or any file to Base64, or decode Base64 back to text or a file, with base64url and data: links.URL Encoder / DecoderPercent-encode or decode text and links, with form encoding (+) and a link's query parameters listed.UUID GeneratorUUID v4, v7, v1, v5 and v3 in bulk, GUID formats, and a checker that shows a UUID's version and time.Hash GeneratorMD5, SHA-1, SHA-2 and SHA-3 hashes of any text in hex or Base64, plus HMAC signatures.Cron Expression GeneratorBuild or check a cron schedule: plain-English meaning and the next run times in any time zone.Diff CheckerCompare two texts and see added and removed lines or words.Markdown to HTMLConvert Markdown to clean, sanitised HTML with a live preview.CSV ↔ JSON ConverterConvert CSV to JSON and back, with quotes and delimiters handled.Case ConverterSentence, lower, upper, title and capitalized case, plus camelCase, snake_case, kebab-case and more.Password GeneratorStrong random passwords, one or a list of up to 50, with the characters you choose. Made in your browser.File Checksum CheckerGet MD5, SHA-1, SHA-256 and SHA-512 checksums of any file and verify downloads.DNS CheckerAll DNS records at once, a comparison of public resolvers after a change, SPF/DMARC checks and reverse lookups.What Is My IPSee your public IP address, country and connection type, plus your browser, OS, screen size and time zone.Email Header AnalyzerCheck SPF, DKIM and DMARC, spot spoofing red flags, find the sending IP and trace each hop with its delay.SVG OptimizerShrink SVG files with SVGO: paste or open several, set precision, prettify or make responsive, strip scripts.Favicon ICO ConverterFavicon generator: a PNG or JPG logo into a multi-size favicon.ico, or the full package with apple-touch-icon and manifest.Schema Markup GeneratorJSON-LD for local businesses, organizations, products, articles, breadcrumbs and FAQs, checked against Google's rules.XML Sitemap GeneratorTurn a list of URLs, with last-modified dates, into a valid sitemap.xml for Google and Bing.Meta Tag GeneratorTitle and description with width checks, Google and share previews, robots, Open Graph and X tags.Open Graph PreviewPreview a link on Facebook, WhatsApp, LinkedIn and X, and check a page's og: tags and share image.llms.txt GeneratorCreate an llms.txt in the llmstxt.org format: summary, key facts and links, imported from your sitemap.Random Number GeneratorFair random numbers in any range, whole or with decimals, with or without repeats, sorted if you like.Time Zone ConverterAny date and time in your zone across world cities, with time differences, UTC offsets and daylight saving handled.

Pasting secrets

These tools run locally, so a JWT or API response you paste isn't sent to us. Even so, rotate any real secret you've pasted into a website, and prefer test tokens when you're only checking a format.

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