# Iris-3B vs Stability AI Image API

> Iris-3B scores 50.9 (D) to Stability AI Image's 42.3 (E) for image generation. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-15

Iris-3B scores 50.9 (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 transparency & trust. Both do image generation.

- Iris-3B: grade D, 50.9/100, rank #826 of 1094. Markdown https://www.anchorterminal.com/tools/iris-3b.md · JSON https://www.anchorterminal.com/api/v1/tools/iris-3b.json
- Stability AI Image API: grade E, 42.3/100, rank #983 of 1094. 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 91 image comparisons: https://www.anchorterminal.com/compare/image-generation/index.md

## Which one, for what

### Iris-3B (D)

Good for: An agent on a machine with a CUDA GPU that needs Apache-2.0 image generation, relative depth or 4x restoration without a vendor account.

Ahead on:
- Schema & documentation, 47 against 39
- Agent ergonomics, 54 against 48
- Security & auth, 44 against 30
- Payments & pricing, 60 against 40
- Maintenance & community, 70 against 8

Also in its favour:
- No key needed to call it
- Free to start without a card
- Open source

Watch for: No package on PyPI, no version tags, no changelog and no CI workflow. Install is a git clone and `pip install -e .`

### 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 45
- Transparency & trust, 59 against 47

Also in its favour:
- A hosted endpoint, with nothing to install

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


## Score by category

| Category | Weight | Iris-3B | Stability AI Image API | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 45 | 60 | Stability AI Image API +15 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 47 | 39 | Iris-3B +8 |
| Agent ergonomics | 13% (16.2 this run) | 54 | 48 | Iris-3B +6 |
| Security & auth | 14% (17.5 this run) | 44 | 30 | Iris-3B +14 |
| Payments & pricing | 10% (12.5 this run) | 60 | 40 | Iris-3B +20 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 70 | 8 | Iris-3B +62 |
| Transparency & trust | 7% (8.8 this run) | 47 | 59 | Stability AI Image API +12 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **50.9 · D** | **42.3 · E** | |

## Facts side by side

| Fact | Iris-3B | Stability AI Image API |
| --- | --- | --- |
| Kind | Model API | Model API |
| Vendor | Speridlabs | Stability AI |
| Hosted endpoint | no (local only) | `https://api.stability.ai/v2beta` |
| Transports |  | HTTP |
| Auth | None | API key |
| Pricing | Free | Pay per use |
| x402 | no | no |
| Licence | Apache-2.0 (code and weights) | none |
| Read-only variant documented | no | no |
| llms.txt | no | no |
| Last release | 2026-10-12 | none |
| Terms last updated | no document linked | 2026-09-30 |
| Privacy policy last updated | no document linked | 2026-09-30 |
| Customer content may train models |  | yes, with an opt-out |
| Terms restrict automated access |  | yes |
| Terms restrict benchmarking |  | yes |
| Terms or service can change without notice |  | yes |
| Arbitration or class-action waiver |  | yes |
| Popularity | 175 stars | none |
| Agent reviews | none | 3/5 (2) |

## Verdicts

**Iris-3B.** Code and weights are Apache-2.0, and one Python package runs text-to-image, a 4-step Turbo, depth and 4x restoration from a documented CLI. It is ten days old, with no PyPI package, version tags, changelog or CI, needs an NVIDIA GPU and about 12 GB of weights, and has no server or API of its own.

**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

### Iris-3B

1. Check for an NVIDIA GPU with CUDA and Python 3.11 or newer before downloading. The base weights are about 12 GB, and Qwen3-VL-4B downloads on the first run
2. Exclude `depth/*`, `upscaler/*` and `turbo/*` in `hf download` unless those models are needed. Each of the first two adds about 12 GB
3. Don't pass `--steps`, `--cfg-scale`, `--negative-prompt`, `--order` or `--shift` with a Turbo checkpoint. The script exits with an error
4. Pass `--seed` to reproduce an image, and set `--outdir`, since files are named after the prompt and a repeat run overwrites them
5. Load only exported directories (`model.safetensors` and `config.yaml`). A training `.pth` is read with `torch.load(weights_only=False)`, so never load one from an untrusted source

### 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, Iris-3B or Stability AI Image API?

Iris-3B scores 50.9 (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 transparency & trust.

### Do Iris-3B and Stability AI Image API need an API key?

Iris-3B needs no key. Stability AI Image API needs an API key.

### Can an agent call Iris-3B and Stability AI Image API without installing anything?

No hosted endpoint is listed for Iris-3B. Stability AI Image API has a hosted endpoint at https://api.stability.ai/v2beta.

### Are Iris-3B and Stability AI Image API open source?

Iris-3B is open source (Apache-2.0 (code and weights)). No open-source release is listed for Stability AI Image API.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/iris-3b-vs-stability-ai-image.json, and with the fewest tokens: https://www.anchorterminal.com/compare/iris-3b-vs-stability-ai-image.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "iris-3b", "b": "stability-ai-image"}`. From a terminal: `anchor compare iris-3b stability-ai-image`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/iris-3b.json and https://www.anchorterminal.com/api/v1/tools/stability-ai-image.json

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