I Built 50 Free Browser-Based Developer Tools - No Signup, No Server Calls

Source: Dev.to

Every developer has that moment: you need to decode a JWT, format some JSON, or convert a timestamp — and you end up on a sketchy site plastered with ads that may or may not be uploading your data to a server in who‑knows‑where.

I got tired of it, so I built DevToolBox — a collection of 50 free, browser‑based developer tools. No signup, no server calls, no tracking. Everything runs in your browser using plain JavaScript.

What’s Inside

Formatters & Validators

• JSON Formatter & Validator – Pretty‑print, minify, and validate JSON with syntax highlighting
• HTML Formatter – Beautify messy HTML
• SQL Formatter – Format SQL queries with keyword uppercasing
• XML Formatter – Indent and validate XML

Encoders & Decoders

• Base64 Encode/Decode – Text and file encoding
• URL Encode/Decode – Handle special characters in URLs
• JWT Decoder – Inspect JWT headers, payloads, and expiry
• HTML Entity Encoder – Named, numeric, and hex entities

Generators

• UUID Generator – v4 UUIDs with bulk generation
• Password Generator – Cryptographically secure passwords with strength indicator
• Lorem Ipsum Generator – Placeholder text by words, sentences, or paragraphs
• QR Code Generator – Pure JS QR encoder with SVG/PNG download

Converters

• Timestamp Converter – Unix epoch ↔ human‑readable
• YAML ↔ JSON – Bidirectional conversion
• JSON ↔ CSV – RFC 4180 compliant
• JSON → TypeScript – Generate TS interfaces from JSON

CSS Visual Tools

• Box Shadow Generator – Visual editor with multi‑layer support
• Gradient Generator – Linear and radial gradients with color stops

Text & Code Tools

• Regex Tester – Real‑time matching with flag support
• Diff Checker – Side‑by‑side text comparison using LCS algorithm
• Markdown Preview – Live preview with pure JS parser

Reference Tools

• HTTP Status Codes – Searchable reference for all 44 status codes
• Cron Expression Parser – Parse cron expressions and show next execution times
• Chmod Calculator – Interactive permission grid with presets
• ASCII Table – Searchable reference (0‑255)

Why Browser‑Based Matters

• Privacy – Your API keys, JWTs, passwords, and config files never leave your machine.
• Speed – No network round‑trip; paste your data, get results instantly.
• Offline capable – After the initial page load, most tools work without an internet connection.
• No rate limits – Format a million JSON objects if you want; it’s limited only by your CPU.

Tech Stack

• Next.js with static site generation (59 pages pre‑rendered at build time)
• Tailwind CSS + shadcn/ui for the UI
• Dark mode with system preference detection
• Zero external API dependencies — every tool is pure JavaScript
• Deployed on Vercel (free tier handles it easily)

What’s Next

I’m planning to keep adding tools based on what developers actually need. If you have suggestions for tools you’d like to see, drop a comment below.

Check it out: toolbox-dev.com

All tools are free forever. No signup required. No data collection. Just open and use.