FileGizmo for developers

Free developer tools

Format JSON, inspect JWT contents, and test regular expressions without pasting sensitive payloads into a server-backed utility. Everything runs locally.

14 tools, all available now0 files uploaded0 accounts needed

Focused utilities

Choose a developer tool

Grouped by what you came to do rather than by file type. Every listed tool follows the same private, browser-based workflow.

Encode and decode

Read and write the usual wire formats.

Base64 encoder and decoderConvert text and Base64 in your browser. URL encoder and decoderFix percent-encoding in links and values. JWT decoderInspect JWT claims without uploading the token. Hash generatorHash text or a file without uploading it.

Format and test

Make something readable, or prove it works.

JSON formatterFormat and validate JSON entirely in your browser. Regex testerTest regex matches and groups with a timeout. Contrast CheckerMeasure contrast, and fix the colour that fails.

Generate

Produce a value you need right now.

UUID generatorMake random v4 identifiers, up to 500. Password generatorStrong passwords made in your browser only. QR code generatorMake a QR code that never expires. Unix timestamp converterRead epoch seconds, millis, or micros.

More tools

Everything else in this cluster.

Number base converterConvert numbers between any bases from 2 to 36. Colour converterConvert colours between hex, rgb, hsl and oklch. HTML entity encoderEscape text for HTML, or decode entities back.

Private by architecture

Inspect data without leaking the data

Debug payloads often include access scopes, customer identifiers, unreleased fields, or tokens copied from a local environment. A quick formatter should not turn that material into a network request. FileGizmo runs its developer utilities in your browser so JSON, JWT contents, regular-expression samples, and matches stay on the device where you opened them. You can verify that behavior in the browser’s own Network panel.

Each utility is deliberately narrow: format and sort JSON, decode the readable parts of a JWT, or test a regular expression against sample text. Errors are translated into useful guidance instead of exposing engine-specific exception dumps. JWT decoding never verifies a signature, and the interface says so clearly; authorization decisions still belong on a trusted server. No account, history sync, or task quota sits between you and a quick inspection.

Straight answers

Frequently asked questions

Are these developer tools free?

Yes. They are free to use without signup, saved history, or daily task limits.

Does the JWT decoder verify signatures?

No. It only decodes the readable header and payload. Always verify the signature and claims in trusted server-side code.

Are JSON, JWTs, or regex samples uploaded?

No. These utilities run locally in your browser and do not send the entered content to FileGizmo servers.