Runs entirely in your browser
Developer tools that respect your data
The small conversions and calculations you do all day, without the ads-first, upload-everything sites.
Tools
Base64 Encoder / Decoder
Encode and decode Base64, with UTF-8 and URL-safe handling that actually works
OpenJSON Formatter & Validator
Format, minify and validate JSON locally in your browser
OpenText Diff Viewer
Compare two texts and highlight added and removed lines
OpenAES Encrypt / Decrypt
Encrypt text with password-based AES-GCM in your browser
OpenCron Expression Parser
See exactly when a cron schedule fires, in the timezone that matters
OpenJWT Decoder
Read the claims inside a token, with expiry in your own timezone
OpenCIDR / Subnet Calculator
Plan IPv4 subnets with the address counts your cloud provider actually gives you
OpenKubernetes Resource Calculator
Convert CPU and memory quantities and see what a Deployment really costs
OpenWhy another set of tools
Every tool here is a static page. There is no backend, no account, and no request leaving your browser — which matters when the thing you are decoding is a production token or an internal config.
- Nothing is uploaded
- All processing happens in JavaScript in your tab. You can open the network panel and watch nothing happen.
- Written from operations experience
- The notes cover the failure modes that actually bite: timezone drift in cron, padding in Base64, unverified JWT signatures.
- Loads instantly
- Static HTML served from a CDN edge. No spinner before you can paste something in.