In this blog post, we will see how I built iamspeed.dev, a fast.com-style LLM API speed benchmark tool that measures Time to First Token (TTFT) and tokens-per-second throughput directly in your browser.
If you have ever stared at a spinning cursor waiting for an LLM response and wondered "is this slow, or is it just me?" this tool is for you.
The tool is designed for quick, lightweight benchmarking, modeled after the fast.com experience for internet speed tests. It uses an extensible provider adapter architecture, making it straightforward to add new providers such as Gemini or Groq. Planned additions include historical results, model comparison mode, and support for local models via Ollama.
iamspeed.dev is an open-source, browser-based benchmarking tool for LLM APIs that measures two key performance metrics: Time to First Token (TTFT) and tokens-per-second throughput. It supports OpenAI and Anthropic providers and stores API keys locally using AES-GCM encryption, with no backend or data transmission.
The Problem That Sparked This
