Inworld has acquired Ultravox to accelerate its speech-to-speech research and voice agent capabilities.Read the announcement
Inworld has acquired UltravoxRead announcement →
Anthropic
Claude Sonnet 4.5 20250929
Going away: Nov 30, 2026
Claude Sonnet 4.5 20250929 is a reasoning model by Anthropic with vision, function calling, web search, prompt caching, structured output — designed for complex, multi-step problem solving where accuracy matters more than speed. It supports a 200K token context window with up to 64K tokens of output. Priced at $3 per million input tokens and $15 per million output tokens. Access Claude Sonnet 4.5 20250929 through Inworld Router with OpenAI SDK compatibility, built-in failover, and intelligent routing across providers.
→Function CallingWeb SearchReasoningPrompt CachingResponse SchemaVisionreasoningCapabilityresponseFormatCapability
Step 1 — Create Router
curl --location 'https://api.inworld.ai/router/v1/routers' \
--header 'Authorization: Basic <your-api-key>' \
--header 'Content-Type: application/json' \
--data '{
"name": "compare-frontier-models",
"defaultRoute": {
"route_id": "default",
"variants": [
{
"variant": {
"variant_id": "anthropic/claude-sonnet-4-5-20250929-a",
"model_id": "anthropic/claude-sonnet-4-5-20250929"
},
"weight": 33
},
{
"variant": {
"variant_id": "anthropic/claude-fable-5-b",
"model_id": "anthropic/claude-fable-5"
},
"weight": 33
},
{
"variant": {
"variant_id": "anthropic/claude-fable-5-1-c",
"model_id": "anthropic/claude-fable-5-1"
},
"weight": 34
}
]
}
}'Step 2 — Chat Completion
curl --location 'https://api.inworld.ai/v1/chat/completions' \
--header 'Authorization: Basic <your-api-key>' \
--header 'Content-Type: application/json' \
--data '{
"model": "inworld/compare-frontier-models",
"messages": [{"role": "user", "content": "Hello!"}]
}'Claude Sonnet 4.5 20250929 pricing and providers
Access Claude Sonnet 4.5 20250929 through Anthropic via Inworld Router or Realtime API. By using the AI provider(s) below you acknowledge you reviewed and agree to their terms listed in the Legal section under the AI provider's name.
| Capabilities | Input modalities | Output modalities | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Anthropic | $3.00 | $15.00 | $0.30 | $3.75 | 200K | 64K | +5 |
Prices in USD per 1M tokens.
Going away: Nov 30, 2026
Other Anthropic models available through Inworld
Compare Claude Sonnet 4.5 20250929 with other Anthropic models available through Inworld Router or Realtime API.
| Provider | Capabilities | Input modalities | Output modalities | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Claude Fable 5 | $10.00 | $50.00 | $1.00 | $12.50 | 1M | 128K | +5 | |||
| Claude Fable 5.1 | $10.00 | $50.00 | $0.25 | $12.50 | 1M | 128K | +5 | |||
| Claude Haiku 5.5 | $0.10 | $0.50 | $0.01 | $0.125 | 1M | 128K | +5 | |||
| Claude Haiku 4.5 20251001 | $1.00 | $5.00 | $0.10 | $1.25 | 200K | 64K | +5 | |||
| Claude Opus 5 | $5.00 | $25.00 | $0.50 | $6.25 | 1M | 128K | +5 | |||
| Claude Opus 5.5 | $4.00 | $20.00 | $0.20 | $5.00 | 1M | 128K | +5 | |||
| Claude Opus 4.8 | $5.00 | $25.00 | $0.50 | $6.25 | 1M | 128K | +5 | |||
| Claude Opus 4.7 | $5.00 | $25.00 | $0.50 | $6.25 | 1M | 128K | +5 | |||
| Claude Opus 4.6 | $5.00 | $25.00 | $0.50 | $6.25 | 1M | 128K | +5 | |||
| Claude Sonnet 5 | $2.00 | $10.00 | $0.20 | $2.50 | 1M | 128K | +5 | |||
| Claude Sonnet 5.5 | $2.00 | $10.00 | $0.20 | $2.50 | 1M | 128K | +5 | |||
| Claude Sonnet 4.6 | $3.00 | $15.00 | $0.30 | $3.75 | 1M | 64K | +5 |
Prices in USD per 1M tokens.
Start building with Claude Sonnet 4.5 20250929
Access Claude Sonnet 4.5 20250929 and every other model through Inworld Router or Realtime API. Create your free account and start routing in minutes.