JSON, JWT, Base64, tokens — dev utilities that respect your privacy
Developers need quick, reliable utilities for everyday tasks: formatting JSON, decoding JWT tokens, generating UUIDs, testing regex, and calculating API costs. This toolkit brings together 19 essential developer tools — all running 100% in your browser with zero server-side processing. Your code, tokens, and data never leave your device. Whether you are debugging an API response, generating a secure password, or creating JSON-LD schema for SEO, these tools work instantly without signup or upload.
Format and convert data structures instantly.
Format, validate, and minify JSON data with syntax error highlighting
Convert between CSV and JSON. Auto-detect delimiter (comma, tab, semicolon)
Live preview Markdown to HTML. GitHub Flavored Markdown (GFM) supported
Decode tokens, encode data, and generate hashes.
Decode and debug JWT tokens locally — no tracking, no server
Encode text to Base64 or decode Base64 to text. UTF-8 safe, URL-safe variant
Compute MD5, SHA-1, SHA-256, SHA-512 — 100% in-browser, instant
Create secure identifiers, passwords, and test regex.
Generate cryptographically secure UUID v4s — bulk, instant, free
Cryptographically secure passwords with strength meter (entropy bits)
Detailed password analysis — entropy, crack time, and pattern detection
Test regular expressions with live highlighting, capture groups, flags
Generate JSON-LD schema, capture screenshots, and create email templates.
Generate JSON-LD schema markup for 12 types — boost Google rich results
Render HTML into a beautiful screenshot — perfect for sharing code
Generate HTML email templates that work in Gmail, Outlook, and beyond
Build beautiful CSS gradients visually — linear, radial, conic with live preview
Build cron schedules visually, human-readable descriptions, next 5 run times
Format and beautify SQL with syntax highlighting — MySQL, PostgreSQL, T-SQL
Extract tables from PDF and export as CSV — table detection, 100% local
The JSON Formatter validates, beautifies, and minifies JSON data with syntax highlighting and tree view. It handles large files (10MB+) without freezing and supports JSON5 syntax. Pair it with the CSV-to-JSON converter for data migration tasks, or the Markdown editor for documentation.
For API debugging, the JWT Decoder parses any JWT token (HS256, RS256, ES256) and shows the header, payload, and expiration status — all client-side, so you never leak tokens to a third-party service. The Base64 encoder/decoder handles UTF-8 text and binary data, while the Hash Generator creates MD5, SHA-1, SHA-256, and SHA-512 hashes instantly.
Need to generate secure identifiers? The UUID Generator creates RFC 4122 compliant v4 UUIDs in bulk. The Password Generator creates cryptographically secure passwords with customizable length, character sets, and entropy estimation. The Password Strength Checker evaluates existing passwords against common attack patterns.
The Schema Markup Generator creates JSON-LD structured data for 12 schema types (Article, FAQ, Product, HowTo, Event, Organization, and more). This is essential for SEO — Google uses structured data to generate rich results and AI engines use it to understand page content. Generate and paste directly into your HTML.
The Token Calculator helps you estimate API costs for LLM-powered features. Enter your prompt length, model, and expected output — it calculates token counts and estimated costs for GPT-4, Claude, Gemini, and open-source models. Essential for budgeting AI features.
The Screenshot tool captures full-page or viewport screenshots directly in your browser — no browser extension needed. The CSS Gradient Generator creates and exports CSS gradient code with a visual editor. The Email Template tool helps you create responsive HTML email templates that work across all email clients.
Yes, all 19 developer tools are 100% free with no signup, no API limits, and no usage caps. Everything runs in your browser — there are no server costs to maintain.
Absolutely. All processing happens locally in your browser. Your JSON data, JWT tokens, passwords, and API keys are never uploaded to any server. This is especially important for JWT decoding and password generation — you never want to send tokens or passwords to a third-party service.
The Schema Markup Generator supports 12 types: Article, FAQPage, Product, HowTo, Event, Organization, LocalBusiness, BreadcrumbList, SoftwareApplication, VideoObject, Recipe, and Review. Each generates valid JSON-LD that you can paste directly into your HTML for Google rich results.
Paste any JWT token and the tool decodes the base64 header and payload, displays the claims in a readable format, checks the expiration date, and shows the algorithm used. It supports HS256, RS256, and ES256 algorithms. The token is never sent to a server — decoding happens entirely in your browser.
Yes. The UUID Generator creates RFC 4122 v4 compliant UUIDs. You can generate 1, 10, 100, or 1000 UUIDs at once and copy them as a comma-separated list, JSON array, or one-per-line format. All generation uses cryptographically secure random number generation.
The Hash Generator supports MD5 (legacy, do not use for security), SHA-1 (deprecated), SHA-256 (recommended), and SHA-512. It also supports HMAC variants for message authentication. All hashing happens locally using the Web Crypto API.
What do you call a kid who stands at the front of the line?
No paywalls, no signups, no data sold. Built by a solo developer who believes useful tools should be accessible to everyone.
☕Support me on Ko-fi— keep tools free100% of proceeds go towards hosting & building more free tools.