17 free browser-based tools for LLM API developers

I kept switching between 5+ different sites just to count tokens, estimate API costs, plan context windows, and format JSON. So I built DevKit AI — a free collection of 17 tools specifically for LLM API workflows. Link: https://devkit-ai.com Token Counter — supports 60+ models (GPT-4, Claude, Gemini, Llama) LLM Pricing Calculator — 64 model families, daily-synced pricing, benchmark scores Context Window Planner — visualize token budget allocation JSON Suite — formatter, diff, JSON-to-TypeScript, JSONPath, schema validator All computation is client-side (Web Workers + WASM) — zero data transmission Next.js 15 on Vercel Pricing data synced daily from official sources No auth, no accounts, no tracking Everything runs in your browser. Free, no signup, available in 8 languages. Curious to hear what tools you wish existed for your LLM workflow!