I built 59 free browser-based dev tools in vanilla JS — here's what I learned
I've been quietly building Antigravity Tools — a collection of 59 free, browser-based developer utilities — and today I'm sharing everything I built and learned. Why vanilla JS? No React, no build step. The main constraint I set for myself: zero dependencies, zero server, zero telemetry . When you paste your JWT token into jwt.io, it goes to their server. When you use an online regex tester, your…
In recent months, I have quietly constructed a collection of 59 free, browser-based developer tools known as Antigravity Tools. This project followed a strict set of guidelines: zero dependencies, no server, and zero telemetry. Every operation runs solely within the user's browser using native APIs, avoiding any reliance on external services or packages.
The tools are built using fundamental web technologies such as Web Crypto API, Canvas API, Web Audio API, and IndexedDB, all of which are readily available in modern browsers.
The 59 tools are divided into eight categories:
1. Security & Auth Tools: JWT Inspector allows users to decode JWT tokens, examining their header, payload, and expiry. RSA & ECC Key Generator enables the creation of 2048-bit key pairs using the SubtleCrypto API. Hash & Password Generator employs SHA-256 and SHA-512 algorithms via Web Crypto for password hashing. PII Masker sanitizes sensitive information from text, removing emails, credit card details, Social Security Numbers, and IP addresses.
2. AI & Prompting Tools: AI Token Counter estimates the computational cost of using popular AI models like GPT-4o, Claude 3.5, Gemini 2.0, and DeepSeek R1. System Prompt Builder structures agent instructions using XML tags and tool definitions, while AI Text Humanizer rephrases robotic AI output into more natural-sounding language. Prompt Cost Trimmer compresses AI prompts by 30-50% to minimize API costs.
3. Dev & Code Tools: JSON Workbench beautifies and validates JSON data, converting it into TypeScript, Python, Go, or PHP equivalents. cURL Converter translates cURL commands into browser-compatible JavaScript fetch, Python requests, Go, or PHP code. Regex Tester offers real-time pattern matching with highlighted capture groups.
Cron Builder provides a visual editor for constructing cron expressions, displaying the equivalent plain-English schedule. Git Command Helper facilitates the creation of undo, squash, and cherry-pick commands through a visual interface.
All of these tools are accessible at https://antigravitytools.app, adhering to the philosophy of empowering developers to work locally and securely without any external dependencies or data collection.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.