Free Developer Tools Online: JSON Formatter, Encrypt, Regex Tester (No Signup)

I use the JSON Formatter at least 10 times a day. Paste messy API response, click beautify, copy the readable version. Two seconds. No terminal, no npm package, no IDE plugin to install.

That's the pattern for all 28 developer tools on Craftisle: they solve a single specific problem, no clicks wasted.

Encryption & Hashing

AES Encrypt/Decrypt — AES-128/192/256 with ECB or CBC mode. Uses Web Crypto API. Key stays in your browser. Good for encrypting config values before storing them in a repo. Not good for encrypting files over 10MB (memory limit).

Bcrypt Hash — adjustable cost factor, verify against existing hashes. "I need to test my auth flow with a real bcrypt hash" — this tool answers that.

Hash Tool — MD5, SHA-1, SHA-256, SHA-512, RIPEMD-160. Drag-drop file hashing. A quick integrity check for downloaded files.

JWT Decoder — paste a token, see header/payload/signature. "This token doesn't decode in jwt.io — let me try locally." The decoding happens client-side, so tokens with sensitive claims stay off third-party servers.

Formatters

JSON Formatter — beautify, minify, validate. Collapsible tree view for large objects. Handles JSON up to about 5MB before the UI chugs. This is our most-used tool by a wide margin.

HTML/SQL/YAML Formatter — each handles indentation and syntax highlighting. SQL formatter respects nested queries and CTEs. YAML formatter catches indent errors in Kubernetes manifests and Docker Compose files before you deploy.

HTML Escape — converts < to < and back. Prevents XSS when embedding user content in HTML. Simple but breaks often enough to justify a dedicated tool.

Converters

Base64/32/58 — text and file encoding. Base58 is Bitcoin-style, no ambiguous characters (0/O, I/l).
CSV ↔ JSON — custom delimiters. Good for 10K-row files; 100K+ rows will slow the UI.
URL Encode/Decode — percent-encoding. Handy for debugging query parameters.
Image to Base64 — embed images as data URIs in HTML/CSS.
Radix Converter — bases 2-36 with live preview.

Developer Tools

Cron Expression Builder — interactive editor, shows next 5 run times. "Did I just set this job to run every minute or every month?" — the preview catches those mistakes.

Regex Tester & Visualizer — real-time match highlighting, captured groups, and an AST diagram view. The visualizer is rated 5 stars for a reason: seeing a regex as a tree makes debugging patterns much faster than staring at /^(?:\d{3}|$\d{3}$)([-/.])\d{3}\1\d{4}$/.

Mermaid Chart Editor — flowcharts, sequence diagrams, Gantt, class diagrams. Live preview, PNG/SVG export. Uses mermaid.js.

SVG Editor — write SVG code, see it render. Good for quick inline graphics.

HTML Visual Editor — WYSIWYG HTML editing. Sandboxed iframe preview (no allow-same-origin for security).

Generators

QR Code Generator — logo support, color options, size control.
UUID v4 Generator — RFC-4122 compliant, batch mode.
Lorem Ipsum — configurable paragraph count.
Random String — uses Crypto.getRandomValues() for cryptographic randomness. Good for API keys and passwords.
Pixel Art — raster → pixel style conversion.
Handwriting Animation — text → animated SVG handwriting. Rated 5 stars.

What to expect

All 28 tools are client-side. Encryption/hashing uses Web Crypto API. File size limit is whatever your browser can hold in memory — Chrome handles ~50MB comfortably, Safari less on iOS.

No tool here handles files in batch. One operation at a time. For batch processing, pdfcraft (the PDF subdomain) is the better option.

FAQ: Free Developer Tools Online

How to format JSON online free?

Use Craftisle JSON Formatter — paste messy API response, click beautify, copy the readable version. Handles up to ~5MB. No install, no signup.

Best free regex tester with visualizer?

Craftisle Regex Tester has real-time match highlighting and an AST visualizer. The tree view makes debugging patterns much faster than staring at raw regex.

How to decode JWT token free online?

Use JWT Decoder — paste a token, see header/payload/signature. Decoding happens client-side, so tokens with sensitive claims stay off third-party servers.

Craftisle QR Generator supports logo, color options, size control. Download as PNG or SVG. Free, no limits.

How to convert CSV to JSON free?

Use CSV ↔ JSON Converter — supports custom delimiters. Good for 10K-row files; 100K+ rows will slow the UI.

Bookmark /tools/json-formatter. If you handle JSON daily, it'll save you 5 minutes per session. Try it with a messy API response right now.

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