Claude API Playground

How ClaudKit Works

ClaudKit is an interactive API playground for Anthropic's Claude. It provides a visual form where you configure every parameter of an API request — model, system prompt, user message, temperature, and max tokens — and instantly see the equivalent code generated in three languages: curl, Python, and JavaScript. The generated code updates in real time as you adjust any parameter, so you can experiment with different configurations and immediately copy working code into your project.

The playground includes a built-in pricing estimator that calculates the cost of each request based on the model you select and the estimated token count of your input and output. A daily usage slider lets you project monthly costs at different request volumes, which is essential for budgeting before committing to a production integration. The estimator uses current Anthropic pricing for Haiku, Sonnet, and Opus models.

For developers who want to test their requests immediately, ClaudKit includes a live API tester. Enter your Anthropic API key, click Send, and see the actual response from Claude rendered in the browser. Your API key is held only in browser memory during your session and is sent directly to the Anthropic API endpoint — it is never stored, logged, or transmitted anywhere else. The complete source code is open on GitHub for anyone to verify this claim.

Features

ClaudKit includes preset request templates for common use cases such as code generation, text summarization, data extraction, and creative writing, so you can start with a working example and customize from there. The code output panel features syntax highlighting for all three languages, making the generated code easy to read and understand. A one-click copy button puts the code on your clipboard ready to paste into your editor or terminal. The model selector includes all available Claude models with their pricing displayed inline. Temperature and max tokens controls include tooltips explaining what each parameter does and recommended ranges for different task types.

Who Uses This

ClaudKit is built for developers integrating Claude into their applications, from solo developers building their first AI feature to engineering teams evaluating the Claude API for production use. Backend developers use it to prototype API calls before writing integration code. Frontend developers use the JavaScript output to add Claude-powered features to web applications. DevOps engineers use the curl output for testing in CI/CD pipelines. Technical writers use it to generate accurate code examples for documentation. If you need prompt templates to use in your API calls, ClaudHQ provides a library of 30+ tested prompts optimized for Claude. For building multi-step workflows that chain multiple API calls together, ClaudFlow offers a visual workflow designer that complements the individual requests you build here.

Privacy

Everything runs locally in your browser. ClaudKit does not send any data to any server other than direct API calls to Anthropic when you explicitly click the Send button with your own API key. No cookies, no tracking, no analytics, no server-side processing. Your API key is never stored in localStorage, cookies, or anywhere persistent — it exists only in browser memory and is discarded when you close the tab. The application is a static HTML, CSS, and JavaScript site. The complete source code is open source on GitHub.