Unit Converter

Convert between length, weight, temperature, volume, area and speed units.

These are the small utilities a developer reaches for a dozen times a day — formatting JSON, testing a regex, hashing a string. Every one of them runs as plain JavaScript in your own browser tab, so pasting in something sensitive (an API response, a token, a connection string) never actually leaves your machine.

Like the rest of the Developer tools, the Unit Converter runs as plain JavaScript in your browser tab. What you type or paste in is never sent anywhere — there's no server round-trip for it to go through.

There's no right moment to reach for the Unit Converter — some people run it once before shipping something, others keep it open and use it every day. Either way, it stays free, there's no limit on repeat use beyond a light rate limit, and nothing about a previous run is remembered the next time you open the page. It's also one of several tools in the Developer category here, so if it turns out not to be quite the right one, the related tools listed below are worth a look before searching elsewhere.

Common questions

Is anything I type sent to a server? No — this tool runs entirely as JavaScript in your browser tab. Whatever you paste in stays on your device.

Can I use this offline? Once the page has loaded, yes — it needs no further network requests to keep working.

Is it safe to paste in real credentials or API keys? Nothing you enter leaves your browser, so it's as safe as any other local tool — though as general practice it's still worth rotating secrets you've pasted anywhere, just in case.

Related Developer tools

A few other developer tools people tend to reach for alongside the Unit Converter:

• JSON Formatter
• JSON Validator
• Base64
• URL Encoder