# Claude Sonnet 5.5 API

Claude Sonnet 5.5 is Anthropic's mid-tier model, positioned to balance speed and intelligence, with adaptive thinking, a 1M-token context window and up to 128K output tokens; list price $2.00 in / $10.00 out per 1M tokens, provider list as at 1 November 2026.

- Provider: Anthropic
- Model ID: claude-sonnet-5-5
- Type: Chat
- Region: AU (can be pinned to Sydney or Melbourne on request)
- Context window: 1,000,000 tokens
- Max output: 128,000 tokens
- Modalities: text, vision, tools, reasoning
- Endpoints: OpenAI Chat Completions https://api.seedrise.ai/v1; Anthropic Messages https://api.seedrise.ai
- Prices checked: 1 November 2026

## Provider list price

Provider list price as at 1 November 2026, per 1M tokens. AUD at a reference rate of 1 USD = 1.53 AUD; invoices use the rate on the day.

| Token type | USD | AUD |
|---|---:|---:|
| Input | 2.00 | 3.06 |
| Output | 10.00 | 15.30 |
| Cached input | 0.10 | 0.15 |

Your Seedrise rate is quoted per account against this list price. Request a rate card: https://seedrise.ai/contact?model=claude-sonnet-5-5

Pinning to an Australian region carries the provider's regional premium on top of the list price shown.

Launch rate (global routing): 1.80 input · 9.00 output per 1M tokens, 10% below Anthropic's published list price, for rate card requests by 31 Jan 2027. Terms (https://seedrise.ai/launch-offer)

Marked AU: can be pinned to Sydney or Melbourne on request, where the Australian-region list price is $2.20 in / $11.00 out per 1M tokens (cache reads $0.11). Without pinning it runs on the provider's global routing.

## Strengths

- Rated fast in Anthropic's latency comparison, against moderate for Opus 5.5
- Adaptive thinking with high as the default effort level
- Same 1M-token context and 128K output limit as Opus 5.5 at half the list price
- Cache reads list at $0.10 per 1M tokens

## Typical use cases

- Interactive coding assistants and IDE agents where response time matters
- Customer-facing chat and support with tool use
- Sub-agents in Claude Code alongside an Opus 5.5 main session
- Document processing and extraction at moderate volume

## Quickstart

A first request with curl. Replace sk-... with your Seedrise key.

```bash
curl https://api.seedrise.ai/v1/chat/completions \
  -H "Authorization: Bearer sk-..." \
  -H "Content-Type: application/json" \
  -d '{"model":"claude-sonnet-5-5","messages":[{"role":"user","content":"Hello"}]}'
```

OpenAI SDK, Python:

```python
from openai import OpenAI

client = OpenAI(base_url="https://api.seedrise.ai/v1", api_key="sk-...")

r = client.chat.completions.create(
    model="claude-sonnet-5-5",
    messages=[{"role": "user", "content": "Summarise this contract in three bullets."}],
)
print(r.choices[0].message.content)
```

Claude Code talks Anthropic Messages, so it points at the root URL:

```bash
export ANTHROPIC_BASE_URL="https://api.seedrise.ai"
export ANTHROPIC_AUTH_TOKEN="sk-..."                     # your Seedrise key
export ANTHROPIC_API_KEY=""                             # clear any personal key
export ANTHROPIC_DEFAULT_OPUS_MODEL="claude-opus-5-5"
export ANTHROPIC_DEFAULT_SONNET_MODEL="claude-sonnet-5-5"
export ANTHROPIC_DEFAULT_HAIKU_MODEL="claude-haiku-5-5"
export CLAUDE_CODE_SUBAGENT_MODEL="claude-sonnet-5-5"
export CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC=1
claude
```

Full guide: https://seedrise.ai/claude-code

## Where it runs

AU: Can be pinned to Sydney or Melbourne on request. Pinning is set per key, not per request.

Claude in Australia: https://seedrise.ai/claude-australia

## Related models

- [Claude Fable 5.1](https://seedrise.ai/models/claude-fable-5-1): US$10.00 input · US$50.00 output per 1M tokens, Global
- [Claude Opus 5.5](https://seedrise.ai/models/claude-opus-5-5): US$4.00 input · US$20.00 output per 1M tokens, AU
- [Claude Haiku 5.5](https://seedrise.ai/models/claude-haiku-5-5): US$0.10 input · US$0.50 output per 1M tokens, AU
- [GPT-6.1 Sol](https://seedrise.ai/models/gpt-6.1-sol): US$2.00 input · US$10.00 output per 1M tokens, Global
- [Gemini 4 Argon](https://seedrise.ai/models/gemini-4-argon): US$2.00 input · US$10.00 output per 1M tokens, Global
- [Kimi K3.1 Pro](https://seedrise.ai/models/kimi-k3.1-pro): US$2.00 input · US$10.00 output per 1M tokens, Global

## FAQ

### What is the model ID for Claude Sonnet 5.5?

Use claude-sonnet-5-5 as the model field, with no vendor prefix. It works on the OpenAI-compatible endpoint at https://api.seedrise.ai/v1 and on Anthropic Messages at https://api.seedrise.ai. GET /v1/models returns the IDs your key can call.

### How does the Seedrise rate for Claude Sonnet 5.5 compare to the list price?

Anthropic's list price as at 1 November 2026 is US$2.00 per 1M input tokens and US$10.00 per 1M output tokens. Seedrise quotes rates per account against the provider's published list price for the same routing. Volume and committed tiers sit below list. Australian-region routing carries the provider's regional premium.

### What is the context window and max output of Claude Sonnet 5.5?

Claude Sonnet 5.5 has a context window of 1,000,000 tokens and a maximum output of 128,000 tokens, per the provider documentation checked on 1 November 2026.

### Can Claude Sonnet 5.5 run in Australia?

Yes. Claude Sonnet 5.5 can be pinned to Sydney or Melbourne on request. Pinning is set per key, not per request, and carries the provider's regional premium.

### When should I choose Claude Sonnet 5.5 over Opus 5.5?

When latency and cost matter more than the extra capability of Opus. Sonnet 5.5 lists at half the Opus 5.5 price with the same 1M-token context, and Anthropic rates it fast against moderate for Opus 5.5.

### Can I use Claude Sonnet 5.5 as the sub-agent model in Claude Code?

Yes. Set CLAUDE_CODE_SUBAGENT_MODEL to claude-sonnet-5-5 on your Seedrise key to keep sub-agent cost down while the main session runs on Opus 5.5.

Seedrise is an independent provider and is not affiliated with or endorsed by Anthropic. Claude is a trademark of Anthropic, PBC.

Model names are trademarks of their respective providers.

Source: https://seedrise.ai/models/claude-sonnet-5-5