Tool index

Free Developer Tools for JSON, API Testing, Regex & More

Explore fast, browser-based developer tools for JSON tools, API testing, regex generation, design tokens, image optimization, and more — all running locally in your browser.

Free • No signup • Fast browser-based workflows

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Signal Playground

Run JavaScript and preview HTML/CSS instantly in your browser.

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Image Truth

Reduce image size without losing quality. Runs locally — no uploads.

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Image Placeholder

Generate placeholder images with simple URLs.

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Flowchart Studio

Turn code, JSON, and plain steps into clean flowcharts instantly.

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Smart Regex Builder

Generate and test regex patterns instantly — no setup required.

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JSON to Form

Turn JSON into editable form UI — no backend required.

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JSON Visualizer

Format, clean, and explore large JSON payloads locally.

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API Mock Generator

Generate realistic API mock data for frontend tests and demos.

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Color System Generator

Generate semantic light/dark design tokens from one color.

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API Request Playground

Test API endpoints fast with local request history.

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Deep Work

Pomodoro timer with focus insights and local session tracking.

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Reset

Quick stress relief tools for browser-based mental resets.

Workspace Hub

Pick up where you left off

Reopen saved workspaces across Signal Playground, API tools, JSON tools, regex, and design systems from one place.

Open workspace hub