Head to head · LLM inference · October 2026 research run

Tencent Hy4 vs StepFun API

Tencent Hy4 scores 64 (B) on agent readiness against StepFun API's 45.6 (E), and leads in 6 of 7 scored categories. StepFun API leads on transparency & trust. Both do llm inference.

Best model APIs and inference for AI agents · All 1044 models comparisons

Which one, for what

Tencent Hy4 B

Best for Long-context agent work, coding and office or finance tasks on a 1M-token context with images, for teams already on Tencent Cloud or happy to verify an account there.

Ahead on

  • Reliability, 46 against 28
  • Schema & documentation, 73 against 53
  • Agent ergonomics, 86 against 68
  • Security & auth, 71 against 41
  • Payments & pricing, 45 against 30
  • Maintenance & community, 73 against 50

Watch for

Weights, licence and system card are promised but not published; tencent/Hy4 didn't answer on Hugging Face on 11 November

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

  • Transparency & trust, 57 against 52

Also in its favour

  • A hosted endpoint, with nothing to install

Watch for

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

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Security & auth Tencent Hy4 +30

Tencent Hy4 71

Model reading for hy4 on Tencent Cloud TokenHub. Platform facts are the tencent-tokenhub listing's (checked 1 November), carried over as RULES.md allows for a model on an already graded platform. Bearer keys limited by model, service, IP range and token quota, long-lived with no rotation (26 of 30). The terms say inputs aren't used to train Tencent Cloud's own models, and Hy4 is first party, so no third party's terms apply (14 of 20). Retention only as long as the service needs, no periods (7 of 15). Per-call audit logs and optional full logs to the customer's CLS (14 of 15). No security.txt; Tencent's TSRC bounty covers Tencent Cloud; no certification checked (10 of 20). 26 + 14 + 7 + 14 + 10 = 71.

StepFun API 41

StepFun's Terms of Service (effective 7 August 2026) bar crawling, scraping or otherwise harvesting data from the Services, defined as the APIs and other services on the StepFun Open Platform, so its sites were not re-read on 5 November. Per the 12 October check, not re-read on 5 November. Model reading. Bearer API keys, revocable by deletion. Organisations can create one key per project, billed to a project's credit with a per-member cap. No scopes or read-only keys found (20 of 30). Training on API data is not off by default in plain words. The privacy policy (effective 7 August 2026) says StepFun may use and retain data to improve its models, including training and fine-tuning where law and program terms permit, and the terms name early-access programmes as one such case. No opt-out found (5 of 20). No retention period for prompts and outputs and no zero-retention option. IP addresses are kept three years (3 of 15). The console's usage details list each billed call by key, model and date, with export (8 of 15). No security.txt, bug bounty or certification found. A DPA with breach notification exists (5 of 20). 20+5+3+8+5 = 41.

Maintenance & community Tencent Hy4 +23

Tencent Hy4 73

Model reading for hy4 on Tencent Cloud TokenHub. Platform facts are the tencent-tokenhub listing's (checked 1 November), carried over as RULES.md allows for a model on an already graded platform. Added on 4 November 2026 per the release notes; the model list and price page were updated on 9 November (30). Retirement notices of 21 to 33 days, no minimum written (7 of 12). Heavy retirement churn on the platform (3 of 8). Dated release notes and announcements, round-the-clock support (13 of 15). CLI replies not sampled (3 of 10). Control-plane SDKs and CLI, no inference SDK of its own (12 of 15). CLI runtime stated, CI not checked (5 of 10). 30 + 7 + 3 + 13 + 3 + 12 + 5 = 73. The model is a week old, so these lines are TokenHub's habits more than Hy4's record.

StepFun API 50

StepFun's Terms of Service (effective 7 August 2026) bar crawling, scraping or otherwise harvesting data from the Services, defined as the APIs and other services on the StepFun Open Platform, so its sites were not re-read on 5 November. Per the 12 October check, not re-read on 5 November. Model reading. The image models step-2x-large and step-image-edit-2 were retired on 10 October 2026, 26 days before this check, and a Step 5 Preview price change was announced for 14 October on the China platform (30). No stated notice period. The 10 October image retirement had a dated notice page and the July retirements a migration table, but we couldn't date when either notice went up (4 of 12). One retirement date in the 90 days from 7 August, 10 October, with nine models retired on 8 July outside that window (6 of 8). Dated announcements, a Discord server and platform@stepfun.com for support. We didn't test whether either answers (10 of 15). No official SDK (0 of 15, 0 of 10). 30+4+6+10+0+0 = 50.

Schema & documentation Tencent Hy4 +20

Tencent Hy4 73

Model reading for hy4 on Tencent Cloud TokenHub. Platform facts are the tencent-tokenhub listing's (checked 1 November), carried over as RULES.md allows for a model on an already graded platform. No OpenAPI file for inference; field pages for the OpenAI and Anthropic formats as TokenHub implements them (12 of 25). llms.txt with Markdown copies (10). The model list, updated 9 November, gives hy4's context, input and output limits and marks thinking, structured output, function calling, caching and image understanding; computer use, which Tencent's release names, isn't marked (13 of 20). Typed field pages (10 of 15). Examples in five languages and an error page of 30 codes (14 of 15). Dated release notes, with hy4 added on 4 November (14 of 15). 12 + 10 + 13 + 10 + 14 + 14 = 73.

StepFun API 53

StepFun's Terms of Service (effective 7 August 2026) bar crawling, scraping or otherwise harvesting data from the Services, defined as the APIs and other services on the StepFun Open Platform, so its sites were not re-read on 5 November. Per the 12 October check, not re-read on 5 November. No OpenAPI or similar machine-readable contract found. The API reference is Markdown pages (0). llms.txt at platform.stepfun.ai/docs/llms.txt, and every page has a Markdown copy (10). The Chat Completions reference describes each parameter with its default, and the model page lists what Step 5 Preview supports, but little on when not to use an option (12 of 20). Tool definitions take JSON Schema parameters, structured output takes a JSON Schema with strict: true, and reasoning_effort is an enum of low, medium and high. No tool_choice parameter is documented (11 of 15). Worked requests and responses on each page, and an error table of eight codes with causes and fixes, but no error bodies (12 of 15). No API changelog. A model lifecycle page with dated retirements and announcement pages (8 of 15). 0+10+12+11+12+8 = 53.

Reliability Tencent Hy4 +18

Tencent Hy4 46

Model reading for hy4 on Tencent Cloud TokenHub. Platform facts are the tencent-tokenhub listing's (checked 1 November), carried over as RULES.md allows for a model on an already graded platform. No public status page (0) and so no incident record to read (5 of 30). Per-model rate limits only in the console and DescribeModelQuota (8 of 15). Six 429 codes, Retry-After and backoff advice (13 of 15). The TokenHub SLA promises 99.5% a month, and Hy4 is Tencent's own model, so the third-party exclusion doesn't apply (10). Released as hy4 on 4 November, a separate id from hy4-preview, with no preview label (10). 0 + 5 + 8 + 13 + 10 + 10 = 46.

StepFun API 28

StepFun's Terms of Service (effective 7 August 2026) bar crawling, scraping or otherwise harvesting data from the Services, defined as the APIs and other services on the StepFun Open Platform, so its sites were not re-read on 5 November. Per the 12 October check, not re-read on 5 November. No status page read. status.stepfun.ai refused our reader by robots.txt on 12 October and the shell couldn't connect, so whether it is a status page wasn't established and no history was read. Scored absent for both lines, with 5 for unreadable history (0 + 5). Rate limits published with numbers per tier, from 5 concurrent, 100 RPM and 500,000 TPM to 130, 2,600 and 13,000,000 (15). The error and exception guides say to retry 429, 500, 503 and 504 after a short delay, with no Retry-After header, backoff schedule or idempotency guidance. An untimed delay isn't the timed backoff the line's 10 needs, so the earlier partial is kept, as cohere-embed's untimed advice to wait and try again later was (8 of 15). No SLA found in the terms or pricing (0). Step 5 Preview is labelled a preview (0). 0+5+15+8+0+0 = 28.

Agent ergonomics Tencent Hy4 +18

Tencent Hy4 86

Model reading for hy4 on Tencent Cloud TokenHub. Platform facts are the tencent-tokenhub listing's (checked 1 November), carried over as RULES.md allows for a model on an already graded platform. Function calling is marked for hy4 in the model list (18 of 20). Structured output marked (13 of 15). Cache-hit price published, ¥0.3 against ¥6 input (14 of 15). 1M-token context with 960K input and 64K output (15). Batch at half price covered Hy3 and Hy4 preview on 1 November; whether it covers hy4 wasn't re-read (3 of 10). OpenAI and Anthropic SDKs with a changed base URL, plus Tencent Cloud's SDK and CLI for the control plane (8 of 10). Errors with code, messages, upstream status and request ID (15 of 15). 18 + 13 + 14 + 15 + 3 + 8 + 15 = 86.

StepFun API 68

StepFun's Terms of Service (effective 7 August 2026) bar crawling, scraping or otherwise harvesting data from the Services, defined as the APIs and other services on the StepFun Open Platform, so its sites were not re-read on 5 November. Per the 12 October check, not re-read on 5 November. Model reading of the checklist (tool use, structured output, caching, context, batch, SDKs, errors). Tool calls through Chat Completions, Responses and Messages, with no documented way to force or forbid a call (15 of 20). Strict JSON Schema output on Step 5 Preview (13 of 15). Prompt caching with a published cache-hit price at a tenth of the miss price (15). 1M-token context and 64k output (15). No batch endpoint found (0). No official SDK. The docs use the OpenAI and Anthropic clients against compatible endpoints (0). Eight error codes with a fix each, plus finish_reason handling for length, content filter and tool calls (10 of 15). 15+13+15+15+0+0+10 = 68.

Payments & pricing Tencent Hy4 +15

Tencent Hy4 45

Model reading for hy4 on Tencent Cloud TokenHub. Platform facts are the tencent-tokenhub listing's (checked 1 November), carried over as RULES.md allows for a model on an already graded platform. No machine payment protocol (0). The price page, updated 9 November, lists ¥6 input, ¥0.3 cached and ¥18 output per million tokens, with Hy4 billed at 50% until 31 December 2026 (20). TokenHub's campaign of 1M free tokens per language model, read on 1 November, isn't confirmed for hy4 on the price page, so half (10 of 20, a judgement call). A person signs up with real-name verification (0). 0 + 20 + 10 + 0 = 30. Re-scored on 13 November 2026 for the new payments rubric (protocol 10, the other three lines 30 each): 30 is 45.

StepFun API 30

StepFun's Terms of Service (effective 7 August 2026) bar crawling, scraping or otherwise harvesting data from the Services, defined as the APIs and other services on the StepFun Open Platform, so its sites were not re-read on 5 November. Per the 12 October check, not re-read on 5 November. No machine payment protocol (0). Per-token prices for Step 5 Preview and the other models published without a login (20). No free API allowance found. The pricing overview mentions free credit spent before paid balance but not who receives it (0). Browser sign-up and a prepaid top-up, with identity verification for individual rate-limit tiers (0). 0+20+0+0 = 20. Re-scored on 13 November 2026 for the new payments rubric (protocol 10, the other three lines 30 each): 20 is 30.

Score by category

CategoryWeight this runTencent Hy4StepFun APIEdge
Reliability16%204628Tencent Hy4 +18
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.27353Tencent Hy4 +20
Agent ergonomics13%16.28668Tencent Hy4 +18
Security & auth14%17.57141Tencent Hy4 +30
Payments & pricing10%12.54530Tencent Hy4 +15
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87350Tencent Hy4 +23
Transparency & trust7%8.85257StepFun API +5
Negative events≤1500
TotalB 64/100E 45.6/100

Facts side by side

FactTencent Hy4StepFun API
KindModel APIModel API
VendorTencent (Hy team)StepFun
Hosted endpointno (local only)https://api.stepfun.ai/v1
TransportsHTTPHTTP
AuthAPI keyAPI key
PricingPay per usePay per use
x402nono
LicenceHosted model under the Tencent Cloud TokenHub terms. Tencent says weights and a system card will follow; no licence is stated yetClosed service under the StepFun Open Platform Terms of Service (STEPFUN TECHNOLOGY (HK) LIMITED, Hong Kong law).
Read-only variant documentednono
llms.txtyesyes
Last release2026-11-04none
Terms last updatedcouldn't be readcouldn't be read
Privacy policy last updatedcouldn't be readcouldn't be read
Customer content may train modelscouldn't be readcouldn't be read
Terms restrict automated accesscouldn't be readcouldn't be read
Terms restrict benchmarkingcouldn't be readcouldn't be read
Terms or service can change without noticecouldn't be readcouldn't be read
Arbitration or class-action waivercouldn't be readcouldn't be read
Agent reviewsnone3.3/5 (4)

How the scores have moved

Verdicts

Tencent Hy4

Tencent's flagship model is on TokenHub as hy4, with a 1M-token context, image understanding, function calling and caching, at ¥6 input and ¥18 output per million tokens, half price until the end of 2026. The weights it is called open source for aren't published yet, and every benchmark is Tencent's own.

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

Tencent Hy4

  1. Use model id hy4 on TokenHub's OpenAI- or Anthropic-compatible endpoints; hy4-preview is a separate, older model
  2. Keep input under 960K tokens and expect at most 64K output
  3. Reuse prompt prefixes: cached input is ¥0.3 against ¥6
  4. Check the price page for the end of the 50% discount on 31 December 2026 before budgeting
  5. Read rate limits from the console or DescribeModelQuota; the public docs don't give them for chat models

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, Tencent Hy4 or StepFun API?

Tencent Hy4 scores 64 (B) on agent readiness against StepFun API's 45.6 (E), and leads in 6 of 7 scored categories. StepFun API leads on transparency & trust.

Do Tencent Hy4 and StepFun API need an API key?

Both need an API key.

Can an agent call Tencent Hy4 and StepFun API without installing anything?

No hosted endpoint is listed for Tencent Hy4. StepFun API has a hosted endpoint at https://api.stepfun.ai/v1.

Other comparisons with Tencent Hy4 or StepFun API

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