# Prism Inference vs StepFun API

> Prism Inference scores 60.1 (C) to StepFun's 44.4 (E) for llm inference. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/prism-inference-vs-stepfun-api
- Markdown: https://www.anchorterminal.com/compare/prism-inference-vs-stepfun-api.md (~2,700 tokens)
- Slim: https://www.anchorterminal.com/compare/prism-inference-vs-stepfun-api.min.md (~630 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/prism-inference-vs-stepfun-api.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-12

Prism Inference scores 60.1 (C) on agent readiness against StepFun API's 44.4 (E), and leads in 5 of 7 scored categories. Both do llm inference.

- Prism Inference: grade C, 60.1/100, rank #535 of 965. Markdown https://www.anchorterminal.com/tools/prism-inference.md · JSON https://www.anchorterminal.com/api/v1/tools/prism-inference.json
- StepFun API: grade E, 44.4/100, rank #889 of 965. Markdown https://www.anchorterminal.com/tools/stepfun-api.md · JSON https://www.anchorterminal.com/api/v1/tools/stepfun-api.json
- Best model APIs and inference for AI agents: https://www.anchorterminal.com/best/inference/index.md
- All 153 models comparisons: https://www.anchorterminal.com/compare/inference/index.md

## Which one, for what

### Prism Inference (C)

Good for: Coding agents that want DeepSeek-V4.1-Flash at a low input price, with no retention, through whichever of the three wire formats the harness already speaks.

Ahead on:
- Reliability, 65 against 28
- Schema & documentation, 82 against 53
- Security & auth, 65 against 41
- Payments & pricing, 30 against 20

Watch for: Two models. The docs mark Gemma 4 31B as request access per organisation, while llms.txt and the keyless catalogue list it as available

### StepFun API (E)

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

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


## Score by category

| Category | Weight | Prism Inference | StepFun API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 65 | 28 | Prism Inference +37 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 82 | 53 | Prism Inference +29 |
| Agent ergonomics | 13% (16.2 this run) | 68 | 68 | even |
| Security & auth | 14% (17.5 this run) | 65 | 41 | Prism Inference +24 |
| Payments & pricing | 10% (12.5 this run) | 30 | 20 | Prism Inference +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 49 | 50 | StepFun API +1 |
| Transparency & trust | 7% (8.8 this run) | 61 | 58 | Prism Inference +3 |
| Negative events | ≤15 | -2 | 0 | |
| **Total** | | **60.1 · C** | **44.4 · E** | |

## Facts side by side

| Fact | Prism Inference | StepFun API |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Prism Technologies Inc | StepFun |
| Hosted endpoint | `https://api.prisminference.com/v1` | `https://api.stepfun.ai/v1` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | Proprietary service under Prism's terms of service. The OpenAPI file declares `LicenseRef-Proprietary`. The Hermes provider plugin repository carries no licence file | Closed service under the StepFun Open Platform Terms of Service (STEPFUN TECHNOLOGY (HK) LIMITED, Hong Kong law). |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-06 | none |
| Terms last updated | 2026-09-09 |  |
| Privacy policy last updated | 2026-09-09 |  |
| Customer content may train models | not found in the text |  |
| Terms restrict automated access | yes |  |
| Terms restrict benchmarking | not found in the text |  |
| Terms or service can change without notice | not found in the text |  |
| Arbitration or class-action waiver | yes |  |

## Verdicts

**Prism Inference.** Three wire formats, a public OpenAPI 3.1 file, per-token prices in a keyless catalogue and zero data retention by default on every tier. The service launched on 24 September 2026 with two models, one of them by request, from a two-person company. No rate-limit numbers, SLA document, free tier or deprecation policy was found.

**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

### Prism Inference

1. Call `GET https://api.prisminference.com/v1/models` at start-up, with no key, and use only ids it returns. Expect 403 on `gemma-4-31b` without organisation access
2. Use base URL `https://api.prisminference.com/v1` for OpenAI clients and `https://api.prisminference.com` with no `/v1` for Anthropic clients
3. Read `error.retryable` before retrying, and wait for `Retry-After` on 429, which covers both key limits and model capacity
4. Send `reasoning_effort: "none"` or `low` when latency matters. Reasoning is on by default and its tokens are billed as output
5. Keep conversation state yourself and send `store: false` on Responses. `previous_response_id`, stored responses and hosted tools aren't supported

### 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, Prism Inference or StepFun API?

Prism Inference scores 60.1 (C) on agent readiness against StepFun API's 44.4 (E), and leads in 5 of 7 scored categories.

### Do Prism Inference and StepFun API need an API key?

Both need an API key.

### Can an agent call Prism Inference and StepFun API without installing anything?

Yes. Prism Inference has a hosted endpoint at https://api.prisminference.com/v1 and StepFun API at https://api.stepfun.ai/v1.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/prism-inference-vs-stepfun-api.json, and with the fewest tokens: https://www.anchorterminal.com/compare/prism-inference-vs-stepfun-api.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "prism-inference", "b": "stepfun-api"}`. From a terminal: `anchor compare prism-inference stepfun-api`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/prism-inference.json and https://www.anchorterminal.com/api/v1/tools/stepfun-api.json

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