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…
Over the past few months, I've been secretly crafting Antigravity Tools — a suite of 59 complimentary, browser-hosted developer utilities. The sole purpose of this project was to create these tools under strict conditions: absolutely no dependencies, no server, and no data collection. My goal was to ensure every function operated within the browser, utilizing only native APIs. This included the Web Crypto API, Canvas API, Web Audio API, and IndexedDB.
The collection is divided into eight primary categories:
1. Security & Authentication Tools
- JWT Inspector: a tool to decode JWT headers, payloads, and verify expiration dates.
- RSA & ECC Key Generator: generates 2048-bit key pairs using the SubtleCrypto API.
- Hash & Password Generator: implements SHA-256 and SHA-512 hashing using the Web Crypto API.
- PII Masker: automatically removes sensitive information like emails, credit card numbers, SSNs, and IP addresses from text.
2. AI & Prompting Tools
- AI Token Counter: estimates the cost of using popular AI services such as GPT-4o, Claude 3.5, Gemini 2.0, and DeepSeek R1.
- System Prompt Builder: allows users to structure agent instructions using XML tags and define tools within these instructions.
- AI Text Humanizer: takes robotic AI-generated text and rewrites it in a more natural, human-like format.
- Prompt Cost Trimmer: compresses AI prompts by 30-50% to help reduce API costs.
3. Dev & Code Tools
- JSON Workbench: a utility to beautify, validate, and convert JSON data into TypeScript, Python, Go, and other programming languages.
- cURL Converter: converts cURL commands into JavaScript fetch, Python requests, Go, and PHP code snippets.
- Regex Tester: a real-time tool for matching text patterns with detailed display of capture groups.
- Cron Builder: a visual editor for creating and testing cron expressions, providing plain-English explanations of the output.
- Git Command Helper: enables users to build and visualize complex Git commands, such as undo, squash, and cherry-pick, graphically.
Every feature of Antigravity Tools is designed to function solely within the browser, utilizing the Web Crypto API, Canvas API, Web Audio API, and IndexedDB for storage and processing. By adhering to these stringent guidelines, the project aims to provide developers with powerful, private, and efficient tools without the need for external servers or data sharing. Access the tools at https://antigravitytools.app.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
