Grok 4.5 API: Access and Usage Guide (Python + curl)

Grok 4.5 is xAI's new flagship model, and developer interest has spiked since launch — our Grok model page has seen it firsthand. This guide covers what Grok 4.5 actually brings, how it compares to Grok 4.3 and 4.20 within the family, how to make your first API call with Python and curl, and how the grok-latest alias keeps your integration current automatically. Every example runs against Onysoft AI Gateway's OpenAI-compatible endpoint, so if you already use the OpenAI SDK, switching is a two-line change.

What Grok 4.5 Brings

Grok 4.5 doubles down on the two things the Grok line is known for: reasoning and freshness. xAI has positioned Grok as a model that stays close to current information since day one, and 4.5 pairs that approach with a stronger reasoning layer. Multi-step analysis, code review, and fast-moving topics — markets, tech news, regulation — are the workloads it targets.

On the spec sheet, the headline number is a 500K-token context window: enough to carry a multi-file codebase, a stack of long contracts, or the full history of an extended agent session in a single request. If you need even more room, there is a 2M-context sibling in the family, covered in the next section.

If you landed here searching "Grok 4.5 vs Grok 4," the short answer: 4.5 is the balanced default for most day-to-day workloads, while 4.3 and 4.20 stay in the lineup for cost-sensitive and huge-context jobs respectively. The API identifier is x-ai/grok-4.5, callable from any OpenAI-compatible tool.

Which Grok? A Family Selection Guide

The current Grok lineup has four models, each answering a different question:

• x-ai/grok-4.5 — the new flagship with a 500K context window. The default for reasoning-heavy work, complex agents, and anywhere output quality comes first.
• x-ai/grok-4.3 — 1M context at economical pricing. Built for high-volume production traffic: summarization, classification, and extraction at scale.
• x-ai/grok-4.20 — a massive 2M-token context, the largest in the family. Use it for entire document archives or repo-scale analysis. An x-ai/grok-4.20-multi-agent variant is tuned for orchestrating multi-agent workloads.
• x-ai/grok-build-0.1 — the code-focused model, tuned for generation, refactoring, and test writing.

A practical rule of thumb: start with 4.5 when quality matters, drop to 4.3 on the endpoints that dominate your bill, and step up to 4.20 only when context genuinely exceeds 500K. Current pricing lives on the model pages, and the same key works across the 708+ model catalog if you want to benchmark Grok against other providers.

Getting Grok 4.5 API Access, Step by Step

You don't need a separate xAI contract to use Grok 4.5 — Onysoft AI Gateway exposes it through a single OpenAI-compatible API, and setup takes about five minutes:

1. Create a free account — pay-as-you-go, no subscription or monthly commitment.
2. Generate an API key with the sk-ony- prefix from the dashboard.
3. Add balance; usage is deducted as you go, and you can see per-request costs in the panel.
4. Try x-ai/grok-4.5 in the Playground before writing code — running the same prompt against 4.3 and 4.20 side by side is the fastest way to pick the right model.
5. Point your SDK's base_url to https://api.onysoft.com/v1, set the model name, and ship.

If you already have an OpenAI integration, migration is a two-line change: base_url and model. The same key unlocks the rest of the catalog too — one balance, one invoice, one API. Teams in Türkiye additionally get local-currency billing and compliant corporate e-invoicing out of the box.

First Request with Python and curl

Because the Onysoft endpoint follows the OpenAI schema exactly, the official openai Python package works as-is:

from openai import OpenAI

client = OpenAI(
    base_url="https://api.onysoft.com/v1",
    api_key="sk-ony-YOUR_KEY",
)

response = client.chat.completions.create(
    model="x-ai/grok-4.5",
    messages=[
        {"role": "user", "content": "Summarize this week's developments in EU AI regulation."}
    ],
)
print(response.choices[0].message.content)

The same request with curl:

curl https://api.onysoft.com/v1/chat/completions \
  -H "Authorization: Bearer sk-ony-YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "x-ai/grok-4.5",
    "messages": [{"role": "user", "content": "Summarize the difference between Grok 4.5 and Grok 4.3."}]
  }'

Add "stream": true to the request body for streaming; function calling (tools) and JSON mode use the same schema as well. Full parameter references, error codes, and per-language examples are in the API documentation.

Stay Current with grok-latest, Keep Costs in Check

The x-ai/grok-latest alias always resolves to the newest flagship Grok — today that's x-ai/grok-4.5; when the next release lands, the alias moves automatically. It's ideal for prototypes, internal tools, and assistants where you simply want the best available Grok with zero code changes at every launch.

For production systems we recommend the opposite: pin an explicit version like x-ai/grok-4.5. Model behavior can shift between releases, and pinning lets you run your eval set against a new version and migrate deliberately instead of being upgraded mid-flight.

Three practical cost levers:

• Route high-volume, simple endpoints to 4.3 and reserve 4.5 for the steps that genuinely need reasoning.
• The 2M context is tempting, but oversized prompts inflate every request — reach for 4.20 only when the context truly demands it.
• Model your monthly spend in the cost calculator: plug in your token volume and compare Grok variants side by side before committing an architecture.