Developer tools

Small, fast utilities we built to go with our guides. Every tool runs entirely in your browser — no accounts, no uploads, no tracking of what you enter.

JWT Decoder

Paste a token, see its header, payload, and expiry instantly — decoded locally, never sent anywhere.

LLM Token Cost Calculator

Model your monthly API bill across Claude, GPT, and Gemini — with prompt caching and batch discounts.

Cron Expression Parser

Turn any cron expression into plain English and see its next run times in your local timezone.

Cron Expression Generator

Pick a schedule with dropdowns and day toggles — get the crontab line plus its next run times.

IP Subnet Calculator

Enter a CIDR block and get the network, broadcast, host range, mask, and usable host count.

Want a tool we haven't built yet? Tell us — the best requests come from readers. Each tool pairs with one of our explainers, from JWTs to LLM cost control.