Stop Sending People PDFs. Turn Them Into an Email List With Codex.

My trainer sent me a message: “Can you make this file so people have to put in an email to get it?”

She already had the valuable part — the content. But every time she sent someone the file, they downloaded it and disappeared. She had no way to know who opened it, follow up, or keep helping them.

Most of us have something like that sitting on our computer. A PDF. A checklist. A guide. A resource list.

So here’s how to turn that file into a webpage that gives people a preview, collects their email, and then unlocks the rest — so the content you already made starts building your audience. I don’t write a line of code to do it, and you won’t either.

What you’re building

Someone opens one link and starts reading your resource in the browser. When they reach the gate, they enter their email. The rest of the guide unlocks on the same page, and they’re added to your email list automatically.

It’s the same setup behind my Blackwell reading guide. The file gets easier to read on a phone, and it stops disappearing into someone’s downloads folder.

Four tools, one job each

• Codex builds and updates the page.
• GitHub stores the website files and keeps a history of changes.
• Vercel publishes the page and gives it a live link.
• Systeme.io saves and tags the email addresses.

Codex handles the technical work. You create the accounts, approve the connections, and decide how the page should look.

Set it up (about ten minutes)

1. Make a folder. Create a folder on your Desktop called My Signup Page and put a copy of one PDF or Word document inside. One guide, one folder, one result.
2. Create a GitHub repository. Make a new private repository with a README, then copy its link from your browser.
3. Connect it to Vercel. Import that repository into Vercel, choose Other as the framework, and deploy. A 404 page is expected for now — there’s nothing to show yet.
4. Prepare Systeme.io. Create a tag called Download and copy your API key.

That key works like a password. Don’t paste it into Codex, GitHub or a document. Put it in Vercel instead: Settings → Environment Variables, name it SYSTEME_API_KEY, choose Production, and save. Codex only needs the name. It never sees the key.

Three prompts to build it

Open Codex and add the My Signup Page folder to your project. Then connect it to GitHub.

Prompt 1 — Connect the folder

Check whether you can access my GitHub repository at [PASTE YOUR REPOSITORY LINK], install any missing tools, and guide me through any sign-in I need to complete. Connect this folder to that existing repository, keeping the document already here, and confirm you’re ready to build.

When Codex says it’s ready, stay in the same conversation and give it the real job.

Prompt 2 — Create the page

Look at https://drerinjacques.com/blackwell as an example of the email signup and unlock I want. Create a page for the document in this folder using my own information.

My name or business: [YOUR NAME]

People should enter their email to unlock the document. Save them in Systeme.io with the Download tag before unlocking, including existing contacts. My key is already in Vercel as SYSTEME_API_KEY; keep it private and keep the document protected until signup.

Show me a preview so I can see how the page looks.

This is the first big payoff: your file is now a real webpage. Read it next to the original. Check the headings, the lists, the links and how it looks on a phone. If you want a different color, title or layout, just say so in plain English.

Why the gate has to be real

One line in that prompt matters more than the rest: keep the document protected until signup.

Some pages only hide the second half with styling. The content is already sitting in the browser, and anyone who knows where to look can read it without entering an email. That’s a decoration, not a gate.

Asking Codex to keep the protected content on the server — and release it only after a successful signup — is what makes it real.

Publish and test

When the preview looks right, publish it.

Prompt 3 — Publish the page

Push the changes to the existing GitHub repository.

Vercel sees the update and publishes the site. Then don’t stop at “it looks finished.” Test the whole journey:

• Unlock it with an email you control, then confirm the contact shows up in Systeme.io with the Download tag.
• Try an email that’s already on your list. It should get the tag without losing its other tags.
• Open a private browser window and make sure the protected part can’t be reached before signup.

Now you know it works for a new person, an existing contact, and someone trying to get around the gate.

Every step and prompt is on my free follow-along guide. Pick one useful file and build your version.

And if you want hands-on help building and launching tools like this, that’s what we do inside Leveraging AI.

Come build with us.