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\n Free AI image generation for Claude and any MCP client.
\n No API key. No billing account. No per-image cost. Just the Google account you already have.\n
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\n\n---\n\n```\ngenerate_image(prompt: \"an orange fox on a white background\", size: \"1200x630\")\n-> images/an-orange-fox-on-a-white-background.jpg 1200x630 0 credits\n```\n\n> **Every image in this README was generated by this server.** The banner above, the crops below, and the\n> logo renders further down. Nothing was touched up by hand.\n\n---\n\n## Why this one is different\n\nEvery other image MCP server bills you. You register for an API key, attach a credit card, and pay per image —\na few cents each, which quietly becomes real money once a model is iterating on a design and throwing away nine\nattempts out of ten.\n\nThis one doesn't, because it isn't calling a paid API at all. It drives **Nano Banana**, the image model inside\n[Google Flow](https://flow.google.com), through the web app you already have access to. Flow charges\ncredits for video. **Images cost zero.**\n\n| | API-based image MCPs | nano-banana-mcp |\n| --------------------- | ------------------------------ | ----------------------------------- |\n| API key | Required | **None** |\n| Billing account | Required | **None** |\n| Cost per image | Cents each, and it adds up | **$0.00** |\n| Setup | Register, key, billing, secret | Sign into Google in a Chrome window |\n| Exact pixel sizes | Rarely | Yes |\n| Reference images | Sometimes | Yes |\n\nThe trade-off is honest and worth stating: it needs a **real Chrome window that you are signed into**, so it can't\nrun headless or in CI. That's the price of not having a bill.\n\n## What it solves\n\nFlow generates in five fixed aspect ratios: 16:9, 4:3, 1:1, 3:4 and 9:16. Real design work almost never lands on one\nof them — an Open Graph card is 1200×630, a repo banner is 1456×180, an avatar is 400×400.\n\nThis server generates at the closest native ratio and crops to the exact size, using saliency detection so the crop\ndoesn't decapitate your subject. Ask for `1200x630`, get a 1200×630 file.\n\n> **What \"exact size\" does and doesn't mean.** The model is not generating at your dimensions — Flow always returns\n> its own native resolution, around 1 megapixel (1376×768 for 16:9, 1024×1024 for 1:1). The exact size is produced\n> here, locally, by cropping and scaling that result. The file you get really is 1200×630; the pixels in it came from\n> a 1376×768 render.\n>\n> That's a genuine convenience when you're going **down** from native, which covers most web work. Going **up** it\n> will still hand you the file you asked for — request 3000×3000 and you get 3000×3000 — but those extra pixels are\n> interpolated, not generated. There is no more detail in them. The server prints a warning when this happens; if you\n> need real resolution beyond native, upscale deliberately with a tool built for it.\n\n**One generation, three sizes.** Same source image, cropped three ways — note how the crop follows the subject\ninstead of blindly taking the centre:\n\n| `1200x630` — Open Graph | `400x400` — avatar |\n| --- | --- |\n|![](\"docs/size-1200x630.jpg\")
| ![](\"docs/size-400x400.jpg\")
|\n\n`1456x180` — repo banner\n\n![](\"docs/size-1456x180.jpg\")
\n\n## Reference images\n\nGive it an image and the prompt stops describing what to *create* and starts describing what to *change*. Feed it a\nflat logo and ask for it letterpressed into cotton paper, or cast as a matte signage object:\n\n![](\"docs/reference-images.jpg\")
\n\nLeft: the source vector, handed in as a reference. Centre and right: two generations from it, four variants each,\n0 credits, about a minute per batch.\n\n```jsonc\ngenerate_image({\n prompt: \"this logo letterpressed into thick warm off-white cotton paper, raking side light\",\n reference_images: [\"assets/logo.png\"],\n count: 4\n})\n\n// iterating on the same reference? don't re-upload it\ngenerate_image({\n prompt: \"same, but with a deeper impression and visible paper tooth\",\n reference_library_names: [\"logo.png\"],\n count: 4\n})\n```\n\nFlow doesn't take a file straight into the composer: it uploads to the project library first, and you pick it from\nthere. Both steps are handled for you, including the confirm click that actually attaches it. Any reference left over\nfrom a previous turn is cleared first — a forgotten one silently changes the image, and the result gets blamed on the\nprompt.\n\n## How it works\n\nFlow has no public API. Its internal generation call is signed with a reCAPTCHA Enterprise token minted by the page's\nown JavaScript, so **it cannot be replayed from outside the browser** — and this project does not try to. That single\nconstraint shapes the whole design.\n\nSo it does what a person would do: type into the composer and press Enter. What's different is how it reads the result.\n\n**It intercepts the page's own network response** instead of watching the library for something new to show up. That\nresponse already carries the media id, the true dimensions and a signed URL, so there's no polling, no guessing which\nthumbnail is yours, and no ambiguity when several generations are in flight. The only fragile part left is typing the\nprompt.\n\n**One request, four responses.** Ask for four variants and Flow doesn't return an array — it sends four separate HTTP\nresponses, staggered by a couple of seconds. Waiting for \"the next response\" quietly drops three of them and looks\nexactly like an account limit. The collector listens to the whole stream and closes on whichever comes first: all\nexpected images, a 20-second silence, or the hard timeout. It never discards what already arrived.\n\n**UI anchors are Material Symbols ligature names** (`crop_16_9`, `image`, `add_2`) and numeric labels (`16:9`, `x4`).\nThose are identifiers, not translatable text, so it behaves the same whether the interface is in English, Spanish or\nJapanese.\n\n**The cost gate closes before sending.** The server reads the cost *Flow itself* computes in its settings panel and\naborts if it exceeds `FLOW_MAX_COST`, which defaults to 0. The refusal happens while refusing is still free. If the\nnumber can't be read, it doesn't send either — it won't guess.\n\n## Requirements\n\n- Node.js 20 or newer\n- Google Chrome\n- A Google account with access to Flow\n\nThat's the whole list. No API key, no cloud project, no billing account, no secret to rotate.\n\n## Install\n\n```bash\ngit clone https://github.com/frannkurt/nano-banana-mcp.git\ncd nano-banana-mcp\nnpm install\nnpm run build\n```\n\n## Setup\n\n### 1. Let the server reach Chrome\n\n**Recommended — your everyday Chrome (version 144 or newer).** No second browser, your own session, extensions and\ntabs:\n\n1. Open `chrome://inspect/#remote-debugging` and tick **\"Allow remote debugging for this browser instance\"**. Below\n it Chrome should show the server running at `127.0.0.1:9222`.\n2. The first time the server attaches, Chrome asks whether to allow it. Accept. The server keeps that connection for\n the whole session, so it doesn't ask again on every image.\n\nThe server finds it on its own: Chrome writes the port to `DevToolsActivePort` inside its user-data folder, and the\nserver reads it there. Leave `FLOW_CDP_URL` unset for this.\n\n**Alternative — a separate Chrome with its own profile.** Chrome won't open `--remote-debugging-port` on your\neveryday profile, which is why this needs a profile of its own (it will look like a fresh Chrome, without your\nextensions). If nothing is found through the option above, the server falls back to port 9222 on its own. The easiest\nway is the bundled launcher (persistent, dedicated profile so you sign in only once):\n\n```bash\nnpm run chrome\n```\n\nIt opens `flow.google.com` in a dedicated profile (`