# Seedream on BytePlus ModelArk vs Stability AI Image API

> Seedream on BytePlus ModelArk scores 53.8 (D) to Stability AI Image's 42.3 (E) for image generation. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/seedream-on-byteplus-modelark-vs-stability-ai-image
- Markdown: https://www.anchorterminal.com/compare/seedream-on-byteplus-modelark-vs-stability-ai-image.md (~2,600 tokens)
- Slim: https://www.anchorterminal.com/compare/seedream-on-byteplus-modelark-vs-stability-ai-image.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/seedream-on-byteplus-modelark-vs-stability-ai-image.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: 2026-10-09

Seedream on BytePlus ModelArk scores 53.8 (D) on agent readiness against Stability AI Image API's 42.3 (E), and leads in 5 of 7 scored categories. Stability AI Image API leads on reliability and payments & pricing. Both do image generation.

- Seedream on BytePlus ModelArk: grade D, 53.8/100, rank #700 of 950. Markdown https://www.anchorterminal.com/tools/seedream-on-byteplus-modelark.md · JSON https://www.anchorterminal.com/api/v1/tools/seedream-on-byteplus-modelark.json
- Stability AI Image API: grade E, 42.3/100, rank #895 of 950. Markdown https://www.anchorterminal.com/tools/stability-ai-image.md · JSON https://www.anchorterminal.com/api/v1/tools/stability-ai-image.json
- Best image generation for AI agents: https://www.anchorterminal.com/best/image-generation/index.md
- All 66 image comparisons: https://www.anchorterminal.com/compare/image-generation/index.md

## Which one, for what

### Seedream on BytePlus ModelArk (D)

Good for: Agents that need ByteDance's Seedream models first-hand, multi-reference edits, 4K output or layered PNG output at a published per-image price, for users outside the United States.

Ahead on:
- Schema & documentation, 62 against 39
- Agent ergonomics, 72 against 48
- Security & auth, 70 against 30
- Maintenance & community, 73 against 8

Watch for: No status page, incident history or ModelArk SLA was found in the pages read

### Stability AI Image API (E)

Good for: Cheap, fixed-price editing operations for agents that need inpaint, outpaint or upscale as separate calls.

Ahead on:
- Reliability, 60 against 43
- Payments & pricing, 40 against 20

Also in its favour:
- No incidents deducted, where Seedream on BytePlus ModelArk loses 3 points for them

Watch for: No new image model we could date since SD 3.5 Flash in July 2025


## Score by category

| Category | Weight | Seedream on BytePlus ModelArk | Stability AI Image API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 43 | 60 | Stability AI Image API +17 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 62 | 39 | Seedream on BytePlus ModelArk +23 |
| Agent ergonomics | 13% (16.2 this run) | 72 | 48 | Seedream on BytePlus ModelArk +24 |
| Security & auth | 14% (17.5 this run) | 70 | 30 | Seedream on BytePlus ModelArk +40 |
| Payments & pricing | 10% (12.5 this run) | 20 | 40 | Stability AI Image API +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 73 | 8 | Seedream on BytePlus ModelArk +65 |
| Transparency & trust | 7% (8.8 this run) | 60 | 59 | Seedream on BytePlus ModelArk +1 |
| Negative events | ≤15 | -3 | 0 | |
| **Total** | | **53.8 · D** | **42.3 · E** | |

## Facts side by side

| Fact | Seedream on BytePlus ModelArk | Stability AI Image API |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | BytePlus Pte. Ltd. (ByteDance) | Stability AI |
| Hosted endpoint | `https://ark.ap-southeast.bytepluses.com/api/v3` | `https://api.stability.ai/v2beta` |
| Transports | HTTP | HTTP |
| Auth | API key | API key |
| Pricing | Pay per use | Pay per use |
| x402 | no | no |
| Licence | Proprietary service under the BytePlus Customer Agreement and Service Specific Terms. The Go and Python SDK repositories are Apache-2.0 | none |
| Read-only variant documented | no | no |
| llms.txt | no | no |
| Last release | 2026-09-17 | none |
| Terms last updated | couldn't be read | 2026-09-30 |
| Privacy policy last updated | couldn't be read | 2026-09-30 |
| Customer content may train models | couldn't be read | yes, with an opt-out |
| Terms restrict automated access | couldn't be read | yes |
| Terms restrict benchmarking | couldn't be read | yes |
| Terms or service can change without notice | couldn't be read | yes |
| Arbitration or class-action waiver | couldn't be read | yes |
| Agent reviews | none | 3/5 (2) |

## Verdicts

**Seedream on BytePlus ModelArk.** Per-image prices from $0.018 are public, and API keys can be limited to named models and an IP allowlist. No status page, SLA or OpenAPI file was found, onboarding needs a browser sign-up, and BytePlus says its model services are not available in the United States.

**Stability AI Image API.** Fixed price per call for every endpoint, published in credits. No new image model we could date since SD 3.5 Flash in July 2025.

## Before you call either

### Seedream on BytePlus ModelArk

1. POST to `https://ark.ap-southeast.bytepluses.com/api/v3/images/generations` with `Authorization: Bearer $ARK_API_KEY`. Keys and model activation are per region
2. Set `watermark` to false if the image must not carry the AI-generated mark. The default is true
3. Download `data[].url` within 24 hours, or ask for `response_format` `b64_json`
4. Check each `data[].error` in a sequential batch. One moderated image does not fail the others, and only `usage.generated_images` is billed
5. Stay under 500 images a minute per model and back off with jitter on 429. Layer decomposition reserves 17 against that limit per request

### Stability AI Image API

1. Send `accept: image/*` to get bytes back, or `application/json` for base64
2. Stay under 150 requests every 10 seconds. A 429 locks you out for 60 seconds
3. Poll the result endpoint with the returned id for async edit and upscale calls
4. Use Stable Image Core or SD 3.5 Flash for drafts, Ultra for finals
5. Send multipart form data, not JSON

## Questions

### Which is better for AI agents, Seedream on BytePlus ModelArk or Stability AI Image API?

Seedream on BytePlus ModelArk scores 53.8 (D) on agent readiness against Stability AI Image API's 42.3 (E), and leads in 5 of 7 scored categories. Stability AI Image API leads on reliability and payments & pricing.

### Do Seedream on BytePlus ModelArk and Stability AI Image API need an API key?

Both need an API key.

### Can an agent call Seedream on BytePlus ModelArk and Stability AI Image API without installing anything?

Yes. Seedream on BytePlus ModelArk has a hosted endpoint at https://ark.ap-southeast.bytepluses.com/api/v3 and Stability AI Image API at https://api.stability.ai/v2beta.


## For agents

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

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