Lovable API: Build with URL

The Lovable API Build with URL feature is in open beta. Create links that open Lovable with your prompt and reference images or web pages ready to send.

The Lovable API Build with URL feature lets you create links that open Lovable with a prompt already written, and optionally with reference images and web pages attached. Whoever opens the link reviews the prefilled prompt and clicks send to start the build. Build with URL is available on all plans.

Each link tells Lovable what to build and optionally what to reference, such as images to work from or a live web page to draw layout and content from. For example:

https://lovable.dev/#prompt=Create%20a%20todo%20app

This link opens Lovable with the to-do app prompt prefilled and ready to send.

Prompt links never start a build on their own. Older links that include autosubmit=true still work, but Lovable ignores the parameter. The prompt and attachments open unsent in the prompt input, and the build starts only when the person clicks send.

Use cases

Prompt links work anywhere you can share a URL:

• Add a Build with Lovable button to your website or product. Anyone who clicks it opens Lovable with your prompt ready to send.
• Recreate or iterate on an existing web page by passing its URL as a reference.
• Share predefined prompts with friends, colleagues, or your audience on social media.
• Suggest a change in an existing project by linking straight into its chat. See Prefill an existing project’s chat.

You can construct the URL yourself, or use the Lovable Link Generator.

Build a link

Start from the Lovable homepage URL and add parameters after the # symbol, separating them with &. The parameters come after #, not after ? as in most URLs:

https://lovable.dev/#prompt=YOUR_PROMPT&images=IMAGE_URL&html=PAGE_URL

Parameters

The link accepts three parameters:

Parameter	Type	Description	Required/Optional
prompt	string	The text describing what to build. Maximum 50,000 characters. Replace special characters with their URL codes (for example, %20 for spaces).	Required
images	string	A publicly accessible image URL used as a visual reference. Repeat the key to add several (images=URL1&images=URL2). JPEG, PNG, and WebP only, and the URL must end in a matching extension such as .png or .jpg.	Optional
html	string	A publicly accessible web page URL. Lovable fetches the page and uses it as a reference for layout, content, and styling. Repeat the key to add several.	Optional

Reference limits

Lovable applies these limits to images and html references:

• images and html share a combined limit of 10 references per link.
• Every URL must be reachable over public http or https, because Lovable’s servers fetch the content. Lovable skips URLs on private networks or localhost, and drops URLs that require a login to load.
• Lovable also drops unsupported image formats (such as SVG and GIF), invalid URLs, and references over 20 MB or too slow to fetch. The rest of the link still loads, with the prompt and the remaining references.

Prefill an existing project’s chat

Prompt links create new projects. To suggest a change in an existing project instead, add prompt to the project’s URL as a normal ? parameter:

https://lovable.dev/projects/YOUR_PROJECT_ID?prompt=Add%20dark%20mode%20support

When the editor opens, Lovable writes the text into the chat input and removes the parameter from the URL, so reloading the page or going back does not apply it again. Lovable never sends the prompt automatically. Whoever opens the link reviews the text and clicks send. If the chat input already holds an unsent message, Lovable keeps that message and ignores the link’s prompt. After the input is cleared, opening the link again applies it.

Use this for follow-up shortcuts, such as linking a teammate directly to a suggested edit in a shared project.

Lovable Link Generator

Use the Lovable Link Generator to create prompt links without encoding URLs yourself. You need to be signed in, because Lovable stores the uploads in your account.

1. Enter your prompt

   Describe what to build, up to 50,000 characters.

2. Add reference images

   The generator uploads each image to your Lovable account and references the upload in the link.

3. Add reference web pages

   Paste each page’s URL. The page must be publicly reachable, because Lovable’s servers fetch it. Images and web pages share the same limit of 10 references per link.

4. Copy the link and share it

   Anyone who opens the link sees your prompt and references prefilled and ready to send.

Build with URL examples

Replace the example values with your own:

Basic prompt link

https://lovable.dev/#prompt=Create%20a%20todo%20app

Reference image

https://lovable.dev/#prompt=Build%20a%20landing%20page%20with%20this%20logo&images=https://img.com/logo.png

Reference an existing web page

https://lovable.dev/#prompt=Recreate%20this%20page&html=https://example.com/index.html

Web page and image together

https://lovable.dev/#prompt=Rebuild%20this%20page%20with%20our%20logo&html=https://example.com/index.html&images=https://img.com/logo.png

Prefill an existing project’s chat

https://lovable.dev/projects/YOUR_PROJECT_ID?prompt=Add%20dark%20mode%20support

Best practices

Follow these practices for reliable prompt links:

• Keep prompts concise and focused on core features.
• For html, use a standard web page. Lovable may skip pages it cannot read as HTML.
• Make sure every image and page URL is publicly reachable.
• Use clear, descriptive language for the best results.
• Replace special characters in the prompt and in URLs with their URL codes to avoid parsing issues.

Opening a link signed in or signed out

What the person opening a prompt link sees depends on whether they are signed in:

• Signed in: Lovable opens with the prompt and references prefilled. They review the text and click send to start the build.
• Signed out, homepage link (lovable.dev/#...): the prompt still prefills immediately. When they click send, Lovable asks them to sign up or log in, then starts the build with the original prompt and references preserved.
• Signed out, Link Generator link: they sign up or log in first, and the prompt then appears prefilled and ready to send.

Limitations

Two limits can make a link fail as a whole:

• Lovable does not shorten a prompt over the 50,000-character limit. It discards the whole link, and the prompt input stays empty.
• Very long URLs can exceed browser length limits. Use the Link Generator for long prompts.

FAQ

Do prompt links still build the app automatically?

No. Every prompt link, including older links with autosubmit=true, opens the prompt and attachments unsent. The build starts when the person clicks send.

Which image formats can I reference?

JPEG, PNG, and WebP, and the image URL must end in a matching file extension. Lovable drops other formats, such as SVG and GIF.

Do my image and page URLs need to be public?

Yes. Lovable’s servers fetch them, so URLs on private networks, localhost URLs, and URLs that require a login do not load. The Link Generator instead uploads images to your account.

How many references can I add to one link?

Up to 10 in total, combining images and web pages.

What happens when a signed-out user clicks a link?

The prompt still opens prefilled. Homepage links prefill immediately and ask them to sign up or log in when they click send. Link Generator links ask them to sign in first and then show the prefilled prompt. Either way, Lovable preserves the prompt and references, and the build starts only when they click send.

Can I prefill the chat for an existing project?

Yes. Open https://lovable.dev/projects/YOUR_PROJECT_ID?prompt=YOUR_PROMPT. Lovable writes the text into the project’s chat input without sending, and Lovable removes the parameter from the URL after applying it.