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
Key tools
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
Technical decisions
- 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!