Unified Image API

OpenRouter launched a Unified Image API providing standardized access to over 30 image generation models from providers including Google, OpenAI, and Black Forest Labs. The API includes a model discovery endpoint with typed capability descriptors, per-provider granularity for parameters and pricing, and support for streaming previews on GPT Image models. This simplifies model switching and reduces integration errors for developers and AI agents.

Introducing the Unified Image API Brian Thomas · On this page Image generation on OpenRouter now has a dedicated API with unified access to 30+ models. Like all our media generation APIs, we’ve standardized the interface for easy model switching, allowed passthrough for unique model capabilities, and provided programmatic access to discover the details of each individual model. We support models from Google, OpenAI, Black Forest Labs, Recraft, ByteDance, Sourceful, Microsoft, and xAI, with more being added all the time. Browse image models https://openrouter.ai/models?output modalities=image | API docs https://openrouter.ai/docs/guides/overview/multimodal/image-generation | Try it in the playground https://openrouter.ai/playground Know What Each Model Can Do Image models differ in ways that break requests. Seedream 4.5 supports 18 aspect ratios; Gemini 3.1 Flash Image supports 14 overlapping, but not identical . Some models generate up to 10 images per call; others cap at 1. Some accept 16 input references; others accept 4. The /api/v1/images/models endpoint returns typed capability descriptors for every model: { "id": "bytedance-seed/seedream-4.5", "supported parameters": { "resolution": { "type": "enum", "values": "1K", "2K", "4K" }, "aspect ratio": { "type": "enum", "values": "1:1", "16:9", "9:16", "..." }, "n": { "type": "range", "min": 1, "max": 10 }, "input references": { "type": "range", "min": 0, "max": 14 }, "seed": { "type": "boolean" } }, "supports streaming": false } Your code can adapt to any model without hardcoding provider differences or battling 400 errors over unacceptable parameters. This is especially useful for agents. Give your coding agent the /api/v1/images/models response and it has everything it needs to pick a model, validate inputs, and generate images without trial-and-error. Per-Provider Granularity Each model may be served by multiple providers. The per-endpoint records /api/v1/images/models/{id}/endpoints give you the definitive truth for each one: which parameters this specific endpoint accepts, what passthrough keys are allowed, streaming support, and granular pricing. curl "https://openrouter.ai/api/v1/images/models/google/gemini-3.1-flash-image/endpoints" Each endpoint also returns a pricing array with the exact billing structure. Different providers charge in different units: "pricing": { "billable": "output image", "unit": "image", "cost usd": 0.04 } Seedream 4.5 charges a flat $0.04 per image. FLUX.2 Pro bills at $0.03 per megapixel so resolution affects cost . GPT-5.4 Image 2 and Gemini 3.1 Flash Image bill per token. No more guessing why a generation cost what it did; the usage object in every response includes the exact cost in USD. One Request Shape, Any Model The API normalizes the fragmented world of image generation into one schema: curl -X POST "https://openrouter.ai/api/v1/images" \ -H "Authorization: Bearer $OPENROUTER API KEY" \ -H "Content-Type: application/json" \ -d '{ "model": "bytedance-seed/seedream-4.5", "prompt": "a red panda astronaut floating in space, studio lighting", "resolution": "2K", "aspect ratio": "16:9" }' Resolution, aspect ratio, quality, output format, background transparency, input references, streaming: all normalized across every provider. When you need provider-specific features like Black Forest Labs’ steps or guidance , pass them through provider.options keyed by the provider slug from the endpoints API. Streaming Previews for GPT Image Models OpenAI’s GPT Image models GPT-5 Image, GPT-5 Image Mini, GPT-5.4 Image 2 support native SSE streaming through the Image API. Set "stream": true and you’ll receive partial image previews as they’re rendered, so users see progress instead of waiting for the full generation. Check the supports streaming field on any endpoint to see if it’s available. FAQ What happens to image generation through chat completions? Until now, we supported image generation via completions and responses. All existing image models continue to be supported here, however new image models will be added exclusively to the dedicated Image API. If you’re using openai/gpt-5-image , openai/gpt-5-image-mini , or openai/gpt-5.4-image-2 , we recommend switching to one of the dedicated image models. The GPT 5 and 5.4 versions generate images through an LLM, so they don’t provide access to the full set of supported parameters and may incur extra inference cost. Can I use provider-specific features? Yes. Each endpoint exposes an allowed passthrough parameters list. Pass provider-specific keys under provider.options keyed by the provider slug. The endpoints API tells you exactly which keys are accepted. How does pricing work? Each endpoint returns granular pricing lines with a billable unit, cost in USD, and optional variant tiers e.g., resolution-based pricing . The usage object in every response includes the exact cost. Tell us what you think and which models you want next in feedback https://discord.gg/fVyRaUDgxW on Discord.