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Free Claude 3.5 Sonnet API on Vercel AI Gateway

Access claude-3-5-sonnet free through Vercel's $5 monthly credit.

Updated 7/2/2026Provider trust 98/1003 code examples

About the Model

Claude 3.5 Sonnet remains one of the most useful Anthropic models for coding, analysis, tool use, and careful writing. It is older than the latest Sonnet line, but still a practical free API target when you want Claude-style output without paying upfront.

Why choose it?

Coding strength: strong at refactors, explanations, and agentic development loops.
Long context: useful for reading larger files and documentation.
Low-friction free access: Vercel AI Gateway monthly credits let you test it without bringing an Anthropic key.

Free access option

Vercel AI Gateway: call anthropic/claude-3.5-sonnet through an OpenAI-compatible endpoint with monthly credits and no credit card required to start.

Choose Claude 3.5 Sonnet for coding-heavy prototypes, then compare the newer Claude Sonnet and Opus alternatives if you need higher capability.

View all free providers for Claude 3.5 Sonnet

How to Access for Free (via Vercel AI Gateway)

Vercel AI Gateway is the most practical free route for Claude 3.5 Sonnet in this catalog. You get monthly gateway credits and can call Anthropic's model through an OpenAI-compatible API without creating a separate Anthropic billing setup first.

Use Claude 3.5 Sonnet for coding, refactors, document analysis, and careful writing. When credits run out, wait for renewal or switch to another free provider in the directory.

Try it in your browser

Pick a model, paste your own free key, and run. Your key is sent once to call the provider and never stored on our servers.

Code Examples

curl

curl https://ai-gateway.vercel.sh/v1/chat/completions \
  -H "Authorization: Bearer $AI_GATEWAY_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"anthropic/claude-3.5-sonnet","messages":[{"role":"user","content":"Refactor this function into smaller pure functions."}]}'

python

from openai import OpenAI

client = OpenAI(base_url="https://ai-gateway.vercel.sh/v1", api_key="AI_GATEWAY_API_KEY")
response = client.chat.completions.create(
    model="anthropic/claude-3.5-sonnet",
    messages=[{"role": "user", "content": "Refactor this function into smaller pure functions."}],
)
print(response.choices[0].message.content)

javascript

import { generateText } from "ai";

const { text } = await generateText({
  model: "anthropic/claude-3.5-sonnet",
  prompt: "Refactor this function into smaller pure functions.",
});

console.log(text);