Claude Sonnet 5.5
Current version: 5.5 updated
Anthropic's everyday model for code, documents, slides and spreadsheets
What's new in Claude Sonnet 5.5
- Direct upgrade of Claude Sonnet 5
- Stronger at building features, fixing bugs, documents, slides and spreadsheets
- Writes and communicates more clearly than Sonnet 5
- Thinking is always on, effort sets depth, speed and cost
- 1M token context, up to 128K output, text, image and file input
What it's the best tool for
- 1M token context, up to 128K output per reply
- Confident at building features and fixing bugs
- Produces polished documents, slides and spreadsheets
- Writes and explains more clearly than Sonnet 5
- Thinking is always on, effort sets depth and speed
- Accepts text, images and files as input
When to reach for something else
- No native image or video generation
- Thinking is always on: high effort means slower replies and more tokens spent
- On the very hardest reasoning tasks, Opus-class models are stronger
- Knowledge is limited to the training cutoff, fresh data has to come in the prompt
- Soft content filter on borderline topics
How Claude Sonnet 5.5 responds
Claude Sonnet 5.5
Four scenarios where it pays for itself
More about Claude Sonnet 5.5
Claude Sonnet 5.5 Online — Anthropic's Everyday Workhorse Model
Claude Sonnet 5.5 is Anthropic's Sonnet-class model, released on September 28, 2026. It is a direct upgrade of Claude Sonnet 5: on NetRoom it took its place, and the old link now leads to this page. Sonnet 5.5 is built for well-scoped everyday work: writing a new feature, finding and fixing a bug, producing a polished document, a slide deck or a spreadsheet. It runs right in your browser.
What's new vs Sonnet 5
The model is especially strong at building features, fixing bugs and producing documents, slides and spreadsheets you can show right away. It writes and explains more clearly than Sonnet 5: reports, code comments and emails read without a rewrite. Thinking is always on, and effort is the lever for depth, speed and cost. Low effort keeps the model responsive in agentic loops where quick steps matter; high effort suits tasks that deserve more thinking time.
1M token context
Sonnet 5.5 handles up to 1M tokens of context and replies with up to 128K tokens at a time. It accepts text, images and files as input. That means an entire monorepo, a data room or a stack of PDFs in a single request, with no chunking and no lost continuity between parts of a document or codebase.
When to pick it
Choose Sonnet 5.5 as the dependable everyday executor: finishing a feature, untangling failing tests, preparing a report or slides from raw data, guiding an agent through a multi-step scenario. For simple jobs such as quick chat or short copy, lighter models will do; for maximum depth on the very hardest reasoning tasks, look at Opus-class models.
Effort to match the task
Thinking in Sonnet 5.5 is always on, so effort is the main lever. Low effort is enough for quick agent steps and small edits; for a heavy refactor or a long report it makes sense to raise effort: the answer arrives later, but the model digs deeper into the task.
How to start
Open NetRoom, pick Claude Sonnet 5.5 from the catalog, top up your balance and work right in your browser. Pay for what you use, keep your chat history and combine the model with image generation and document tools in one interface.
Version history of Claude Sonnet 5.5
| Version | Date | What changed |
|---|---|---|
| 5.5 current |
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| 5.0 |
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| 4.6 |
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Use Claude Sonnet 5.5 via the API
The same engine, straight from your code: one key and one balance for text, images, video and sound. Pay only for the requests you make.
curl https://netroom.ai/api/v1/chat/completions \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"model": "anthropic/claude-sonnet-5.5", "messages": [{"role": "user", "content": "Hello"}]}'The format is OpenAI SDK compatible — point base_url at https://netroom.ai/api/v1 and use your NetRoom key.
The model id is already in the example. The full parameter reference and prices live in GET /api/v1/models and in the docs.
Try Claude Sonnet 5.5
right now
Free access to basic models. No card, no obligations.