Claude Sonnet 5 Is Here: Opus-Level Agentic Performance at Sonnet Pricing
On June 30, 2026, Anthropic released Claude Sonnet 5 (model ID claude-sonnet-5), calling it "the most agentic Sonnet model yet." It's a big step up from Sonnet 4.6 on reasoning, tool use, coding, and knowledge work — and Anthropic says its performance now sits close to Opus 4.8, at a fraction of the cost. Read the full announcement on Anthropic's blog.
What's New
Claude Sonnet 5 is built to work autonomously for longer stretches: making plans, calling tools like browsers and terminals, and finishing multi-step tasks that used to require a bigger, pricier model. Anthropic also reports a lower rate of undesirable behaviors compared to Sonnet 4.6, making it safer to run in agentic setups where the model is taking real actions.
Key specs:
- Context window: 1M tokens
- Pricing: $2 / $10 per million tokens (input/output) at introductory pricing through August 31, 2026 — after that it moves to the standard $3 / $15
- Availability: the default model on Claude.ai's Free and Pro plans, also available to Max, Team, and Enterprise users, and via the Claude API, Claude Code, Claude Platform, Amazon Bedrock, Google Vertex AI, and Microsoft Foundry
How to Actually Try It for Free (and Where "Free" Gets Fuzzy)
If you just want to chat with it, this part is easy: Claude Sonnet 5 is the default model on Claude.ai's Free plan — no credit card, no API key, just sign in and start chatting. That's genuinely free, but it's the consumer product, not an API you can build with.
For API access, it gets murkier. Vercel AI Gateway already lists anthropic/claude-sonnet-5 — but it charges the exact same introductory pricing as Anthropic's own API ($2/$10 per million tokens). It's not a special deal on this model. The only free component is Vercel's standard new-account perk: $5 of gateway credit every 30 days, shared across every model on the gateway, not something Sonnet 5 gets specifically. At $10 per million output tokens, that $5 disappears fast — enough to kick the tires, not to build on.
So, realistically:
- Want to just use it? Claude.ai Free plan — genuinely free, chat only.
- Want to test the API cheaply? A fresh Vercel AI Gateway account's $5-per-30-days credit will get you a handful of requests before you're paying real money.
- Building something real? You're paying the introductory $2/$10 rate (or $3/$15 after August), whichever platform you call it from.
Where Else You Can Reach It
Beyond direct API access and Vercel AI Gateway, Claude Sonnet 5 is also available through Claude Code, Amazon Bedrock, Google Vertex AI, and Microsoft Foundry — useful if your stack is already committed to one of those clouds.
Sources: Anthropic — Introducing Claude Sonnet 5, Vercel AI Gateway model listing, TechCrunch