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…
I have constructed a collection of 59 free, browser-based developer utilities called Antigravity Tools. Each tool is built using vanilla JavaScript, meaning there are no dependencies, no server, and no telemetry involved. The main purpose behind this project was to ensure every operation runs exclusively within the browser using native APIs.
The 8 categories of tools include:
- Security & Auth Tools: JWT Inspector, which decodes JWT header, payload, and checks expiry locally; RSA & ECC Key Generator, generating 2048-bit key pairs through SubtleCrypto; and Hash & Password Generator, employing SHA-256/SHA-512 via Web Crypto.
- AI & Prompting Tools: AI Token Counter, estimating costs across GPT-4o, Claude 3.5, Gemini 2.0, and DeepSeek; System Prompt Builder, structuring agent instructions with XML tags and tool definitions; AI Text Humanizer, rephrasing robotic AI output into natural writing; and Prompt Cost Trimmer, compressing prompts by 30-50% to reduce API costs.
- Dev & Code Tools: JSON Workbench, beautifying, validating, and converting to TypeScript, Python, and Go types; cURL Converter, converting cURL to JavaScript fetch, Python requests, Go, and PHP; Regex Tester, providing real-time match highlighting with capture group display; and Cron Builder, a visual editor for cron expressions with plain-English output.
- Git Command Helper, assisting users in building undo/squash/cherry-pick commands visually.
Written by urgent.news from Dev.to's reporting — not their text. Machine-written — may contain errors; check the original before relying on it.
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