Model card

Qwen3.5 397B

sdn-qwen3.5-397bReasoningLive in the catalog

The flagship open-weight model of the Qwen3.5 generation: a 397B mixture-of-experts (17B active) that works a problem through before answering. It sits deliberately between the budget reasoners and the frontier tier — the pick when the analysis genuinely matters but frontier pricing doesn't.

Context window262K tokens

Input · per Mtok$0.6

Output · per Mtok$3.6

Served bySideren engine

Where it earns its keep[01/03]

01Flagship-class open-weight reasoning
02262K context for long documents and histories
03Thinking priced the same as direct answers

Capabilities

Tool callingYes

Strict, schema-faithful tool calls, enforced by the engine on every request — safe to build an agent loop on.

ReasoningYes

Thinks before it answers. Budget max_tokens generously — hidden reasoning counts against it.

VisionNo

Text-only.

Behind the endpoint[02/03]

One endpoint. Served by our engine.

Qwen3.5 397B is served through the Sideren engine — zero-downtime serving is the design target, not a status-page apology. You request it by name; everything else is our problem.

Call it by name

curl https://api.sideren.io/v1/messages \
  -H "x-api-key: sdn_your_key" \
  -H "content-type: application/json" \
  -d '{
    "model": "sdn-qwen3.5-397b",
    "max_tokens": 1024,
    "messages": [{ "role": "user", "content": "Hello" }]
  }'

OpenAI-style clients work too — send the same model name to /v1/chat/completions with a Bearer key. See the docs for both dialects.

Your agent doesn't change.
Everything underneath does.

$export ANTHROPIC_BASE_URL=https://api.sideren.io

Get a key Read the docs

Start free · no card · Starter from $5/mo

One endpoint. Served by our engine.

Your agent doesn't change.Everything underneath does.

Your agent doesn't change.
Everything underneath does.