The Grok 4.5 API is xAI's frontier reasoning model served as a hosted endpoint, so you can send prompts and receive completions without running any infrastructure of your own. On GPTProto it sits behind an OpenAI-compatible interface: point your existing openai SDK at our base URL, drop in a grok 4.5 API key, and the model is live in your stack in minutes.
Grok 4.5 is tuned for agentic software engineering — multi-step tool calling, code generation, and long-context reasoning across large repositories. It takes text input and returns text output, and exposes a native reasoning_effort parameter so you can trade latency for deeper reasoning on the hardest tasks.
Why developers choose the Grok 4.5 API on GPTProto:
- Affordable pricing — $1.2/1M input and $3.6/1M output tokens, a standing 40% off the standard rate, billed per token with no monthly minimum.
- One key, every model — the same grok 4.5 API key also calls grok-4.3, grok-code-fast-1, and 100+ other models, so you can benchmark or fall back without opening new accounts.
- No waitlist — sign up, top up, and get grok 4.5 API access the same day.
Grok 4.5 vs grok 4.3: 4.5 raises tool-calling accuracy and reasoning depth for technical workflows, while grok 4.3 stays a cheaper pick for lighter chat and drafting.
