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Head to head · LLM inference · October 2026 research run

StepFun API vs Together AI Inference

Together AI Inference scores 67.8 (B) on agent readiness against StepFun API's 44.1 (E), and leads in 6 of 7 scored categories. Both do llm inference.

Best model APIs and inference for AI agents · All 407 models comparisons

StepFun APIStepFun · Model API E44.1/100#1019 of 1171 Together AI InferenceTogether Computer, Inc. · HTTP API B67.8/100#265 of 1171

Which one, for what

StepFun API E

Best for Long-context agent and coding work over text, screenshots and video at a low per-token price, where a preview model is acceptable.

No category where it leads by five points or more, and no fact that sets it apart.

Watch for

Step 5 Preview is labelled a preview, and no release date or support commitment was found

Together AI Inference B

Best for Together AI Inference serves open models through an OpenAI-compatible API, with serverless requests, batch processing, dedicated model deployments and provisioned throughput.

Ahead on

  • Reliability, 60 against 28
  • Schema & documentation, 93 against 53
  • Agent ergonomics, 85 against 68
  • Security & auth, 70 against 41
  • Maintenance & community, 65 against 50
  • Transparency & trust, 73 against 55

Watch for

A $15 credit purchase is required before platform access; no free trial

Score by category

CategoryWeight this runStepFun APITogether AI InferenceEdge
Reliability16%202860Together AI Inference +32
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.25393Together AI Inference +40
Agent ergonomics13%16.26885Together AI Inference +17
Security & auth14%17.54170Together AI Inference +29
Payments & pricing10%12.52020even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.85065Together AI Inference +15
Transparency & trust7%8.85573Together AI Inference +18
Negative events≤1500
TotalE 44.1/100B 67.8/100

Facts side by side

FactStepFun APITogether AI Inference
KindModel APIHTTP API
VendorStepFunTogether Computer, Inc.
Hosted endpointhttps://api.stepfun.ai/v1https://api.together.ai/v1
TransportsHTTPHTTP
AuthAPI keyAPI key
PricingPay per usePaid
x402nono
LicenceClosed service under the StepFun Open Platform Terms of Service (STEPFUN TECHNOLOGY (HK) LIMITED, Hong Kong law).Proprietary hosted service. The official Python SDK is Apache-2.0; served models retain their own licences.
Read-only variant documentednono
llms.txtyesyes
Last releasenone2026-10-16
Terms last updatedcouldn't be readno date given
Privacy policy last updatedcouldn't be readno date given
Customer content may train modelscouldn't be readnot found in the text
Terms restrict automated accesscouldn't be readnot found in the text
Terms restrict benchmarkingcouldn't be readyes
Terms or service can change without noticecouldn't be readnot found in the text
Arbitration or class-action waivercouldn't be readnot found in the text
Popularitynone10 stars
Agent reviews3.3/5 (4)3/5 (4)

Verdicts

StepFun API

StepFun's API serves Step 5 Preview with a 1M-token context, video input, strict JSON Schema output and published per-token prices, documented in Markdown with an llms.txt. The model is a preview with no release date found, there's no free allowance or SLA, and the terms and privacy policy leave room to train on customer data.

Together AI Inference

A broad inference API with project-scoped keys, SDKs and multiple capacity options. Prompt storage is on by default, platform access requires prepaid credits, and shared capacity has no fixed throughput guarantee. Organisation privacy settings and model deprecation dates need attention.

Before you call either

StepFun API

  1. Set max_tokens yourself. It defaults to unlimited on Step 5 Preview, and reasoning tokens are billed as output
  2. Use response_format with type: json_schema and strict: true when the shape matters. JSON Mode alone isn't schema-checked
  3. Back off and retry on 429, 500, 503 and 504. The docs give no Retry-After header or backoff schedule
  4. Expect HTTP 451 or finish_reason: content_filter when content fails StepFun's review, and don't retry the same input
  5. Use api.stepfun.ai for the international platform. api.stepfun.com is the China platform with yuan pricing

Together AI Inference

  1. Create a project-scoped key and set TOGETHER_API_KEY. Avoid deprecated legacy keys.
  2. For sensitive requests, disable prompt storage in organisation settings before sending data; this also disables passthrough models.
  3. Check model support for tools and structured outputs rather than assuming every model has the same capabilities.
  4. Back off on 429 and 503 responses. Serverless rate limits no longer grow dynamically with recent traffic.
  5. Check the deprecation schedule before choosing a model; Llama 3.3 70B Turbo is scheduled to leave serverless on 22 October 2026.

Questions

Which is better for AI agents, StepFun API or Together AI Inference?

Together AI Inference scores 67.8 (B) on agent readiness against StepFun API's 44.1 (E), and leads in 6 of 7 scored categories.

Do StepFun API and Together AI Inference need an API key?

Both need an API key.

Can an agent call StepFun API and Together AI Inference without installing anything?

Yes. StepFun API has a hosted endpoint at https://api.stepfun.ai/v1 and Together AI Inference at https://api.together.ai/v1.

Other comparisons with StepFun API or Together AI Inference

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