Coding · Do this yourself

Sell a pay-as-you-go PDF generation API.

How it makes money: Charge developers $15 per credit pack for a pay-as-you-go PDF generation API.

Agent setup: Advanced · Needs custom code (Cursor) and hosting you maintain. How we rate this

Found on Reddit in r/SideProject (1 thread).

🔥 0 posts this week · 0 likes

Based on u/Sad-Guidance4579 on Reddit (opens in new tab)

Where this came from (Reddit)

Developers who rarely generate PDFs resent monthly subscriptions for occasional use.

The threads (in our words)

Reddit blocks automated reads, so we couldn’t record upvote or comment counts. The business below is our own design inspired by these threads.

Who it’s for

Developers, small SaaS teams and freelancers making invoices or reports.

Adapt it to your industry

  • Start with one niche or customer type, then expand.
  • Ask your first 10 customers what they would pay before you build more.
  • Keep a human check on anything sent in a customer’s name.

Step by step

  1. Wrap an open-source HTML-to-PDF engine in a simple API on Vercel.
  2. Add API keys and credit balances in Supabase.
  3. Sell credit packs with Stripe Checkout; credits never expire.
  4. Have an agent write docs and code samples for each language.
  5. Get found through comparison pages and dev communities.
  6. Set uptime alerts and check usage weekly.

Ready-to-copy prompt

Write the docs page for an HTML-to-PDF API: auth with an API key, one POST endpoint, options for page size and margins, and examples in curl, JavaScript and Python.

Start with AI

Opens the AI with this guide and the prompt filled in.

Open in ChatGPT (opens in new tab)Open in Claude (opens in new tab)Open in Grok (opens in new tab)
Time
1–3 hoursOur estimate

Your autonomous stack

Autonomy: Agents ship fixes, answer users and post updates. Your part: Weekly: approve releases and read the support log (about 1 hour).

Every layer an agent-run business needs, in order. Prices are public list prices, checked Oct 16, 2026.

  1. Agent (the brain): Grok Bot (agent + scheduled routines) (opens in new tab) (Included with The X Subscription Premium $30/mo (Super $100/mo for more usage; Plus $8 does not include Grok Bot)). Grok Bot runs the business day to day: writes, answers, decides small things and reports to you. Claude Code or Codex are alternatives.
  2. Build and hosting: Cursor (opens in new tab) (Free tier · Plus $8/mo · Premium $30/mo), Vercel hosting (opens in new tab) (Hobby free · Pro $20/mo), Supabase database (opens in new tab) (Free tier · Pro from $25/mo). The product or service your customers use.
  3. Payments: Stripe payments (opens in new tab) (No monthly fee · 2.9% + 30¢ per card payment). Automatic checkout and receipts. Other options: PayPal Checkout (3.49% + 49¢) or Lemon Squeezy (5% + 50¢, handles sales tax).
  4. Customer acquisition: Buffer (scheduled X posts) (opens in new tab) (Free plan (3 channels, 10 queued posts each) · Essentials $5/mo per channel, billed yearly), beehiiv newsletter (opens in new tab) (Free up to 2,500 subscribers). Agent-written SEO pages, scheduled X posts and a weekly newsletter.
  5. Delivery: Grok Bot (agent + scheduled routines) (opens in new tab) (Included with The X Subscription Premium $30/mo (Super $100/mo for more usage; Plus $8 does not include Grok Bot)). A Grok Bot routine delivers the product or result as soon as someone pays.
  6. Support: Grok Bot (agent + scheduled routines) (opens in new tab) (Included with The X Subscription Premium $30/mo (Super $100/mo for more usage; Plus $8 does not include Grok Bot)). Grok Bot answers the support inbox; anything unclear is flagged for you.
  7. Monitoring and schedule: Grok Bot (agent + scheduled routines) (opens in new tab) (Included with The X Subscription Premium $30/mo (Super $100/mo for more usage; Plus $8 does not include Grok Bot)). Grok Bot scheduled routines run each day: send, check for failures, alert you if something breaks.
  8. Analytics: Google Analytics (opens in new tab) (Free). Tracks visits, signups and sales so the agent can report what works.
  9. Human checkpoint: Weekly: approve releases and read the support log (about 1 hour).
  10. Price: charge $15 per pack (prepaid credit packs). Offer the first 3 customers a founding price for honest feedback.
Monthly cost$30–$110/monthFree tiers → paid plans of the tools above. Card fees come out of each sale.
What you could earn · EstimateEstimate: 40 packs a month × $15 = $600/moOur estimate, not a fact or a promise. It’s simple math if you land these customers at this price.
Details: source, numbers and tags

What they did

Developers buy credit packs instead of a monthly plan to turn HTML into PDFs; it runs itself. We designed this business from real Reddit threads; it is an idea for you to build, not a description of the posters’ businesses.

How it went

Found on Reddit in r/SideProject (1 thread). Upvote and comment counts weren’t retrievable, so none are shown. On X, 0 posts matched our search for this idea in the 7 days to 2026-10-16.

Worth knowing

Watch for abuse (huge files) and cap request sizes.

Difficulty
BeginnerOur rating
Time to build
Not reportedOur estimate
Monthly cost
Not reported
Revenue
Not reportedWe only show revenue the source states
Engagement
No public countThe source shows no number
X buzz
0 · 0 posts in 7 days0 likes, 0 reposts, 0 replies, 0 quotes on 0 top posts · fetched Oct 16, 2026 · query: ("pdf api" OR "html to pdf") (pricing OR subscription OR expensive OR alternative) -is:retweet lang:en

Posted · Added Oct 16, 2026

Original builder recipe

  • ChatGPT
  • Claude
  1. Wrap an open-source HTML-to-PDF engine in a simple API on Vercel.
  2. Add API keys and credit balances in Supabase.
  3. Sell credit packs with Stripe Checkout; credits never expire.
  4. Have an agent write docs and code samples for each language.
  5. Get found through comparison pages and dev communities.
  6. Set uptime alerts and check usage weekly.

Tags

Read the original

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