How to Add E-Signatures to a Lovable App

Lovable turns a plain-English description into a working web app, which makes it one of the most popular ways to ship a project without writing the scaffolding by hand. If you're new to the workflow, our explainer on what vibe coding is covers the basics. The catch shows up the moment your app needs a real signature on a contract, an invoice, or an onboarding form. A drawn squiggle in a canvas element is not a legally-binding e-signature. You need an audit trail, a tamper-evident record, and compliance handling.

“Adding e-signatures to a Lovable app” means connecting the app Lovable generated to a real e-signature service so a recipient can sign a document and you get back a verifiable, signed PDF. With TurboSign and the TurboDocx Quickstart Skill, that connection takes just three short prompts. This post is the overview. For the line-by-line SDK walkthrough, jump to the full step-by-step integration guide.

Most apps that handle agreements eventually need a signature: invoices, statements of work, NDAs, waivers, lease forms, partner contracts. Lovable can render a beautiful version of any of those documents. What it cannot do on its own is produce the legal artifact, the signed record with a timestamp, signer identity, and an audit trail that holds up if anyone questions it later.

You could try to build signing yourself: a canvas to draw on, a database to store the image, some logic to stamp it onto a PDF. That path looks short and is not. A realistic from-scratch build would run several days once you account for the moving parts, roughly a day or two for the signing UI and PDF stamping, another day for storing signed documents and their metadata durably, and a day or more wiring up email delivery, status tracking, and the audit logging that makes the signature defensible. None of that is your product. Connecting a hosted signing API skips all of it, and the US e-signature compliance and European e-signature compliance work stays on TurboDocx infrastructure rather than your weekend project.

There's a maintenance argument too. A hand-rolled signing flow is code you now own forever: you patch it when a browser changes how canvas events fire, you reissue certificates, you answer the support ticket when a signed PDF won't open. Pointing your Lovable app at a hosted signing API moves all of that off your plate. Your app keeps doing the one thing it's good at, presenting the document, while the signing service owns the parts that have to be exactly right every time.

We ran this end to end on June 8, 2026, starting from an empty Lovable project. The whole build took about 12 minutes across three prompts, including one Vite dependency hiccup that Lovable fixed on its own by restarting the dev server. The point is how little signing-specific work it took: once the Quickstart Skill is installed, you describe what you want in plain English and the agent makes the right TurboSign calls. The full timestamped walkthrough is on the hub: I built a signable invoice app with Lovable.

The second prompt is the whole trick. Instead of pasting API docs and hoping the model guesses the right method names, you install the TurboDocx Quickstart Skill so Lovable gets ground truth. From the project, run the open-source skills CLI:

npx skills add TurboDocx/quickstart

Create a free account at app.turbodocx.com (your first 5 signatures each month are free), grab your key from Settings → API Keys, and add the integration's environment variables:

TURBODOCX_API_KEY=your_api_key_here
TURBODOCX_ORG_ID=your_org_id_here
TURBODOCX_SENDER_EMAIL=you@company.com
TURBODOCX_SENDER_NAME=Your Company Name

With the skill installed and the key in place, you tell Lovable what you want in plain English and it does the wiring. The skill reads your key from the environment rather than baking it into source, so nothing sensitive ends up in your generated code.

By default the first version of the app created a signature that sat in an “under review” state, a deliberate staging step before anything reaches the signer. The third prompt fixed that in one go: “skip the review step and go straight to the full send.” Behind the scenes that swaps createSignatureReviewLink for sendSignature, which emails the document to the recipient immediately. Two methods, one decision: stage a review, or fire and forget. You choose by describing the behavior you want, and the agent picks the right call.