OpenAI API Alternatives (October 2026): Claude, Gemini, Grok, DeepSeek, Kimi, Mistral, OpenRouter and Local Models Compared

Before switching for price alone, look at OpenAI's own budget options: GPT-6 Luna costs $0.10 / $0.50 per million tokens, and half that with Batch or Flex processing.

Prices below are standard list prices per million input / output tokens in USD, from each provider's pricing page, checked October 15–17, 2026.

The alternatives at a glance

OpenAI-compatible base URLs

Token counts differ between tokenizers, so the cheapest price per token isn't always the cheapest price per task. Run your own prompts through two or three candidates before deciding.

Which one fits your use case

Provider notes

Anthropic Claude

Claude is the most common choice for coding agents and long, tool-heavy tasks. Its OpenAI-compatible endpoint is described by Anthropic as "primarily intended to test and compare model capabilities". It ignores several OpenAI parameters and doesn't support prompt caching, so use the native Messages API for production. Prices and caching: Claude API pricing; keys: How to get a Claude API key.

Google Gemini

The only major provider with a meaningful free API tier. Watch two scheduled price increases: Gemini 4 Argon doubles on December 1, 2026, and 3.8 Flash and 3.6 Flash double on January 1, 2027. New accounts prepay at least $5 to unlock paid models. Full prices and limits are in Google's Gemini API pricing.

xAI Grok

Grok 4.7 matches GPT-6.1 Sol on input price and costs 40% less on output. There's no free API tier, and prompts of 200,000 tokens or more are billed at double rates for the whole request. See Grok API.

DeepSeek

The lowest list prices here, and half price off-peak, which covers the entire US working day. Thinking mode is on by default and its tokens are billed as output. See DeepSeek API pricing.

Kimi (Moonshot AI)

Kimi K3 has a 1M-token context and is aimed at software engineering and deep reasoning, but at $3 / $15 it costs more than Claude Sonnet 5.5. Rate limits depend on how much you've recharged, and a $1 account gets only 3 requests per minute. See Kimi API.

Mistral

A French model company. Mistral Large lists at $0.5 / $1.5, with 50% off for batch processing and up to 90% off cached input. Mistral also has a free plan for its own apps; check its site for current API trial terms.

OpenRouter

An aggregator that routes to many providers through one OpenAI-compatible API. It passes token prices through without markup, but charges 5.5% (minimum $0.80) when you buy credits by card, and a 5% fee on bring-your-own-key usage above its monthly free allowance. Check those fees against the convenience of a single key.

Running models yourself

Ollama serves local models with an OpenAI-compatible API at http://localhost:11434/v1, and any string works as the key. vLLM is the usual choice for serving open models at higher throughput on your own GPUs. You trade per-token fees for hardware and operations.

How to switch without breaking things

With the official openai SDK, switching is usually three lines:

from openai import OpenAI

client = OpenAI(
    api_key="YOUR_PROVIDER_KEY",
    base_url="https://api.x.ai/v1",  # the provider's OpenAI-compatible URL
)
resp = client.chat.completions.create(
    model="grok-4.7",  # the provider's own model name
    messages=[{"role": "user", "content": "Hello"}],
)

Then check the things that differ between providers. What is an OpenAI-compatible API? covers each in detail:

1. Model names. Every provider uses its own IDs.
2. Silently ignored parameters. Some layers accept response_format, seed or reasoning_effort and do nothing with them.
3. Tool calling and JSON output. Test your real tool schemas; small format differences break agents.
4. The Responses API. Fewer providers support it than Chat Completions. Codex, for example, needs it.
5. Prompt caching. Often available only through the provider's native API, and it can change your bill several-fold.
6. Errors and rate limits. Status codes differ. xAI returns 400 for a wrong key where OpenAI returns 401, which matters if your code only catches authentication errors.
7. Data handling. Free tiers often use your data for training; check each provider's terms before sending customer data.

A safe migration: run the new provider in parallel on a sample of real traffic, compare cost per completed task and failure rates for a week, then move over.

One key for many providers

If you want to compare or mix several of these, a gateway saves you from managing separate accounts. api.foo, the service that publishes these docs, serves Claude, GPT, Gemini, Grok, DeepSeek, Kimi and other models through one OpenAI-compatible endpoint (https://api.foo/v1), plus Anthropic and Gemini native formats, billed per token from one balance. Model names and prices are on the api.foo pricing page. Going direct to a provider gives you its full feature set and any discounts it offers, such as DeepSeek's off-peak pricing.

Related

• What is an OpenAI-compatible API?
• OpenAI API pricing and calculator
• Free LLM APIs in 2026
• Claude Code vs Codex vs Cursor vs OpenCode

Sources

Checked October 15–17, 2026: OpenAI pricing; Anthropic pricing and OpenAI SDK compatibility; Gemini API pricing and OpenAI compatibility; xAI pricing; DeepSeek pricing; Kimi pricing; Mistral pricing; OpenRouter quickstart and FAQ; Ollama OpenAI compatibility.