The Best Free Developer Tools You're Not Using in 2026

I'm a tool hoarder. I bookmark everything, forget most of it, and rediscover the same tools six months later through a different Hacker News thread. But some tools actually stick. The ones I keep coming back to share a few traits: they load instantly, they work offline, they don't need an account, and they do one thing well. Here are 9 free browser-based developer tools I use regularly. All of them run entirely client-side — your data never leaves your browser. 1. SigCraft — Email Signature Generator What it does: Generates professional HTML email signatures that actually render correctly across Gmail, Outlook, Apple Mail, and Thunderbird. Why it's good: Email signatures are deceptively hard. What looks fine in Gmail breaks in Outlook because Microsoft still uses Word's rendering engine (yes, in 2026). SigCraft uses battle-tested table-based HTML that handles these quirks. You fill in your details, pick a layout, customize colors, and copy the HTML. No account needed. The pain it solve