Guides
Short, practical walkthroughs for common jobs — each with a worked example you can reproduce, and an honest note on the limits. Every guide uses a tool that runs in your browser.
How to merge PDF files without uploading them
Combine PDFs privately: merge them in your browser so the files never leave your computer, check that nothing is uploaded, and know the limits.
How to decode a JWT locally — and why it matters
Read a JSON Web Token's header and claims without sending it anywhere, understand exp and iat, and learn the difference between decoding and verifying.
How to convert a curl command to Python requests
Turn a curl command — for example one copied from browser DevTools — into Python requests code, with a worked example and a map of common curl flags.
How to calculate an IPv4 subnet, with a worked example
Find the network address, broadcast address, usable host range and mask for any IPv4 address and CIDR prefix — by hand, step by step, then check it.
How to convert JSON to YAML without breaking your config
Convert JSON to YAML for Kubernetes, CI and app configs — a worked example, the quoting rules that keep values from changing type, and what doesn't round-trip.
How to sign a PDF in your browser
Add a handwritten signature to a PDF on your own device, without accounts or uploads — plus what a drawn signature is legally and when you need a digital one.