DevOps tools that run in your browser
Small utilities I got tired of searching for. Every one of them is pure client-side JavaScript — no sign-up, no backend, and nothing you paste ever leaves your machine.
Visual Subnet Calculator
Split and join CIDR blocks visually
Divide a network into subnets by clicking, then join them back. Shows address ranges, usable IPs, netmasks and host counts — and encodes your whole division into a shareable link.
Base64 Encoder / Decoder
Encode and decode, UTF-8 safe
Convert text to and from Base64, including URL-safe output. Handles full UTF-8 correctly, so emoji and non-Latin scripts survive the round trip.
JWT Decoder
Inspect header, payload and expiry
Decode a JSON Web Token and read its header and claims, with human-readable timestamps and a live expiry check. Decoding only — the signature is never verified and the token never leaves the page.
YAML ↔ JSON Converter
Convert manifests both ways
Translate between YAML and JSON in either direction, with clear parse errors. Built for Kubernetes manifests, CI configs and Terraform variable files.
Cron Expression Explainer
Read a schedule in plain English
Translate a 5-field cron expression into a sentence and preview the next run times. Understands ranges, steps and lists, plus the usual @daily style shorthands.
UUID & Password Generator
Cryptographically secure values
Generate RFC 4122 v4 UUIDs and strong random passwords or API keys using the browser’s Web Crypto API — real entropy, not Math.random().
Why these run locally
Plenty of online converters and decoders quietly ship your input to a server. That is a bad habit to build when the thing in your clipboard is a Kubernetes secret or a production JWT. Everything here is implemented in the JavaScript that ships with the page: you can read the source, disconnect your network, and the tools still work.
Ideas for tools worth adding? Tell me — the list is deliberately easy to extend.