Anthropic releases Claude Sonnet 4.6 with 1 million token window
Anthropic just dropped Claude Sonnet 4.6, and it's a noticeable step up from the last version.
Released on February 18, 2026, this upgrade is open to both free and Pro users, bringing smoother coding, better computer interactions, and smarter planning tools.
One cool highlight: there's now a beta feature with a 1-million-token context window, so you can work on longer projects without getting interrupted.
Developers preferred Sonnet 4.6 about 70%
Sonnet 4.6 isn't just faster; it's also more efficient and affordable than before, approaching Opus-level intelligence.
In early user testing, developers preferred this new model about 70% of the time thanks to its improved context handling and logic skills.
It's also better at actually finishing tasks without tripping up or making false claims, a big relief for anyone who relies on AI for long stretches of work (though it still can't quite match expert humans yet).