Free developer tools — 18 utilities in one directory
18+ free browser-based developer tools: Base64 encode/decode, JWT decoder, JSON formatter & diff, CURL to fetch converter, QR code generator, cron builder, image compressor, regex tester, UUID generator, hash tools, and more. No signup — runs locally in your browser. Each tool has its own URL you can bookmark—grouped across JSON & API, encoding & media, security, and SEO utilities. We pair tools with the blog so you get both "how" and "when not to," not just a single textarea. No account, no install: open the page, paste input, and copy the result.
Why use browser-based developer tools?
Privacy: Encoding, hashing, image compression, and QR generation run locally in your tab whenever possible—you are not batch-uploading files to a random server. Speed: no install, no version drift: the tool matches the page you have open. Shareability: send a colleague a URL that always opens the right workflow—JSON diff, CURL conversion, cron builder, or sitemap export—without bundling a desktop app. For teams, that cuts onboarding time: the JWT and hash tools explain limits (for example, JWT decode is not signature verification) right on the page.
How to choose the right tool
| If you need… | Start here |
|---|---|
| Turn plain text into a Base64 string for JSON or config | Base64 encode |
| Read a Base64 string back to UTF-8 text | Base64 decode |
| Inline an icon or small asset (data URL / raw Base64) | Image to Base64 |
| Preview an image you only have as Base64 or a data: URL | Base64 to image |
| Read JWT header, payload, and exp/iat (debug, not auth) | JWT decoder |
| Pretty-print or minify JSON with validator hints | JSON formatter |
| Compare two JSON documents side by side with highlighted diffs | JSON diff checker |
| Paste a cURL command and get fetch() or axios code | CURL ↔ fetch converter |
| Encode or decode URL strings and Unicode query values | URL encoder / decoder |
| Generate scannable QR codes (URL, WiFi, vCard, email) | QR code generator |
| Build and validate cron expressions with human-readable hints | Cron expression generator |
| Shrink JPG, PNG, or WEBP files before upload or embed | Image compressor |
| Try a regex against sample text with visible matches | Regex tester |
| Issue random v4 UUIDs for IDs and fixtures | UUID generator |
| Convert Unix time ↔ readable dates (local & UTC) | Timestamp converter |
| Build SHA-256 or MD5 hex digests for checksums | SHA256 / MD5 hash generator |
| Experiment with bcrypt cost and copy password hashes | bcrypt hash generator |
| Hand off a sitemap.xml for Search Console or static hosting | XML sitemap generator |
All tool entry points
XML sitemap generator
Paste URLs, download sitemap.xml for SEO handoffs and static hosts.
JWT decoder
Inspect header, payload, and exp claim. Signature not verified in-browser.
Base64 encode
UTF-8 text to Base64 with autodetect, copy, and download.
Base64 decode
Base64 to readable text with common whitespace tolerance.
Image to Base64
Local file to data URL and raw Base64, no upload.
Base64 to image
Paste a payload, preview, and copy a normalized data URL.
Regex tester
Pattern, flags, live highlights — invalid regex surfaces as a clear error.
UUID generator
Cryptographically random v4 UUIDs — batch generate and copy locally.
Timestamp converter
Unix seconds or milliseconds ↔ calendar dates — local and UTC.
JSON formatter
Format, validate, or minify JSON in the browser — instant error hints.
URL encoder / decoder
Percent-encode or decode text and query values — Unicode-safe.
SHA256 / MD5 hash generator
Fingerprint strings with SHA-256 or MD5 — copy-ready hex output.
bcrypt hash generator
Generate bcrypt password hashes with adjustable cost — runs locally.
JSON diff checker
Compare two JSON objects—highlight added, removed, and changed fields.
CURL ↔ fetch converter
Convert curl, fetch, and axios snippets—preserve headers and bodies.
QR code generator
Custom QR codes for URLs, WiFi, WhatsApp—PNG/SVG download with logo support.
Cron expression generator
Visual cron builder with presets, human-readable output, and next-run preview.
Image compressor
Compress JPG, PNG, WEBP locally—quality slider, batch upload, before/after preview.