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OpenAI · Image Generation

GPT Image 2.5 Sunburst API

OpenAI GPT Image 2.5 most capable model for image generation and high-precision editing

$0.295–$0.589 per image, by size · priced before it runs · no subscription

About OpenAI GPT Image 2.5 Sunburst

GPT Image 2.5 Sunburst is an image model from OpenAI. It renders 3 sizes and is billed per image at the size you ask for, from $0.295 per image. The image comes back on a hosted URL that does not expire. You can call it without an account, an API key or a subscription.

Use GPT Image 2.5 Sunburst for

  • Product shots, ad creative and social images generated per request
  • Illustrations and diagrams an agent produces alongside its written answer
  • Concept art and mood boards, several variations from one prompt
  • Placeholder and test imagery inside an app's own pipeline

GPT Image 2.5 Sunburst specs

Endpoint
POST /api/v1/images/generations
Price
$0.295–$0.589 per image, by size
Sizes
1024×1024, 1536×1024, 1024×1536
Output
A hosted image URL that does not expire

How to call GPT Image 2.5 Sunburst

Pass openai/gpt-image-2.5-sunburst as the model field. The first request returns a 402 with the exact price; a signed retry runs it, and the client libraries fold the two into one call — how the payment works. Request and response shapes are in the docs.

curl -X POST https://blockrun.ai/api/v1/images/generations \
  -H "Content-Type: application/json" \
  -d '{"model": "openai/gpt-image-2.5-sunburst", "prompt": "a lighthouse at dawn, watercolor", "size": "1024x1024"}'

GPT Image 2.5 Sunburst or another image model

Every image model here takes the same request on the same endpoint, so trying another is a one-line change to the model field. The AI Image Generator page lists all of them side by side.

GPT Image 2.5 Sunburst API questions

How much does the GPT Image 2.5 Sunburst API cost?

$0.295–$0.589 per image, by size, including the per-call transaction fee. The exact price is quoted in the 402 response before anything is generated, and you pay per request with no subscription.

Do I need an API key to use GPT Image 2.5 Sunburst?

No. Each request carries its own payment, so an agent or script can call GPT Image 2.5 Sunburst with no account and no key. Teams that prefer one can use an API key with card or invoice billing instead.

How do I call GPT Image 2.5 Sunburst?

Send a POST to /api/v1/images/generations with "model": "openai/gpt-image-2.5-sunburst". The request shape is shown above, and the same endpoint serves every image model on the catalog, so switching models is a one-line change.

What sizes does GPT Image 2.5 Sunburst support?

1024×1024, 1536×1024, 1024×1536. Each size has its own price, and the one you request is the one you pay for.

GPT Image 2.5 Sunburst or another model — which should I use?

Compare it with Nano Banana ($0.0535 per image), Nano Banana 2 ($0.0955 per image), Nano Banana Pro (from $0.106 per image) in the table above. They take the same request on the same endpoint, so you can try two on one prompt and keep the one you prefer.

Two ways to run this

Get an API key

Sign in, get a key, and call the same endpoints with usage billed to your account. For teams that want one invoice instead of one wallet.

Get an API key 

Or let your agent pay per call, in USDC

No account, no API key. Three steps, and the last one is the request this page is about.

  1. 01
    Point your agent at BlockRun

    Install ClawRouter, or add the BlockRun MCP server to Claude Code, Cursor, Codex or OpenClaw. Any OpenAI-compatible client works too — change the base URL, nothing else.

    curl -fsSL https://blockrun.ai/ClawRouter-update | bash
  2. 02
    Fund a wallet with USDC

    Send USDC to a wallet on Base, Solana or Arc. There is no account to create and no API key to issue: the wallet is the account, and it pays per call.

  3. 03
    Call GPT Image 2.5 Sunburst

    The first call returns HTTP 402 with the exact price, your agent signs it, and the answer comes back. Payment settles on-chain; nothing is charged if the call fails.

    curl -X POST https://blockrun.ai/api/v1/images/generations \
  -H "Content-Type: application/json" \
  -d '{"model": "openai/gpt-image-2.5-sunburst", "prompt": "a lighthouse at dawn, watercolor", "size": "1024x1024"}'
ClawRouter setup →How paying per call works →

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