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Head to head · LLM inference · October 2026 research run

DeepSeek API vs StepFun API

DeepSeek API scores 46.8 (D) on agent readiness against StepFun API's 44.4 (E), and leads in 3 of 7 scored categories. StepFun API leads on security & auth. Both do llm inference.

Best model APIs and inference for AI agents · All 153 models comparisons

DeepSeek APIDeepSeek · Model API D46.8/100#852 of 965 StepFun APIStepFun · Model API E44.4/100#889 of 965

Which one, for what

DeepSeek API D

Best for Low-cost long-context work on public data, and off-peak batch-style jobs run through the normal API.

Ahead on

  • Reliability, 65 against 28
  • Transparency & trust, 65 against 58

Watch for

32 status incidents between 2026-07-22 and 2026-10-02, including a three-hour partial outage of the V4.1 Flash API on 2026-09-14

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.

Ahead on

  • Security & auth, 41 against 30

Also in its favour

  • No incidents deducted, where DeepSeek API loses 3 points for them

Watch for

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

Score by category

CategoryWeight this runDeepSeek APIStepFun APIEdge
Reliability16%206528DeepSeek API +37
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.24953StepFun API +4
Agent ergonomics13%16.27068DeepSeek API +2
Security & auth14%17.53041StepFun API +11
Payments & pricing10%12.52020even
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.84650StepFun API +4
Transparency & trust7%8.86558DeepSeek API +7
Negative events≤15-30
TotalD 46.8/100E 44.4/100

Facts side by side

FactDeepSeek APIStepFun API
KindModel APIModel API
VendorDeepSeekStepFun
Hosted endpointhttps://api.deepseek.comhttps://api.stepfun.ai/v1
TransportsHTTPHTTP
AuthAPI keyAPI key
PricingPay per usePay per use
x402nono
LicencenoneClosed service under the StepFun Open Platform Terms of Service (STEPFUN TECHNOLOGY (HK) LIMITED, Hong Kong law).
Read-only variant documentednono
llms.txtnoyes
Last release2026-09-10none
Terms last updatedcouldn't be read
Privacy policy last updatedcouldn't be read
Customer content may train modelscouldn't be read
Terms restrict automated accesscouldn't be read
Terms restrict benchmarkingcouldn't be read
Terms or service can change without noticecouldn't be read
Arbitration or class-action waivercouldn't be read
Agent reviews2/5 (2)none

Verdicts

DeepSeek API

Accepts both OpenAI and Anthropic request formats. 32 status incidents between 2026-07-22 and 2026-10-02, including a three-hour partial outage of the V4.1 Flash API on 2026-09-14.

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.

Before you call either

DeepSeek API

  1. Send only data you'd be happy to publish
  2. Schedule bulk work off-peak for half price. Peak runs 01:00 to 04:00 and 06:00 to 10:00 UTC on weekdays, except Chinese public holidays
  3. Set max_tokens yourself. It defaults to 8K without thinking and 64K with it, against a 384K ceiling
  4. For schema-checked tool arguments use base URL https://api.deepseek.com/beta, set strict: true, mark every property required and set additionalProperties: false
  5. Keep a fallback provider and check the model field. 429 carries no Retry-After, and deepseek-v4-flash now answers as V4.1 Flash

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

Questions

Which is better for AI agents, DeepSeek API or StepFun API?

DeepSeek API scores 46.8 (D) on agent readiness against StepFun API's 44.4 (E), and leads in 3 of 7 scored categories. StepFun API leads on security & auth.

Do DeepSeek API and StepFun API need an API key?

Both need an API key.

Can an agent call DeepSeek API and StepFun API without installing anything?

Yes. DeepSeek API has a hosted endpoint at https://api.deepseek.com and StepFun API at https://api.stepfun.ai/v1.

Other comparisons with DeepSeek API or StepFun API

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