~/about
Patrick, the maker of LocalFirstTools
LocalFirstTools is 28 free browser-only developer tools for JSON, JWT, Base64, hashing, UUIDs and timestamps, built by Patrick in the Netherlands. Input is processed in the browser tab and never uploaded.
It is a collection of 28 free tools for formatting JSON, inspecting tokens, converting data and working with text and files in your browser.
LocalFirstTools is the 28-tool developer toolkit at localfirsttools.com, built by Patrick in the Netherlands, and isn't affiliated with other projects with similar names.
Meet the developer
- Name
- Patrick
- Based in
- The Netherlands
- Role
- Developer and maker of LocalFirstTools
- Developer profile
- Patrick on GitHub
A tool should not need your data on a server
Developer tools often handle data you would rather keep to yourself: API responses, configuration files and authentication tokens. LocalFirstTools runs these operations in the browser. The site delivers the code; the code works on your device.
You can check that behaviour yourself. Load a tool, clear the Network panel and run a sample. Then disconnect and repeat. The 10-second verification lives on the how-it-works page, and the bundle manifest identifies the JavaScript delivered with each build.
Built for a specific task
Use the JSON Formatter to make a payload readable, the JSON Minifier to compact it, or the JWT Decoder to inspect claims. Decoding a token does not verify its signature. Each tool explains what it does and where its limits are.
For a reproducible bug, send a small, made-up example through the contact page. Keep real credentials and customer data out of reports.
Where LocalFirstTools is listed
Directory profiles that point at this site are collected on the featured page, currently SaaSHub and AZN8.
Citeable first-party measurements (JSON minify, Base64 overhead, UUID and hash lengths) live on the stats page.
Updated October 14, 2026