Selling niche API documentation is a low-overhead way to hit

I've been implementing this as a side-stream for my team, and the efficiency is wild. We aren't writing from scratch; we're basically using GPT-4 as a high-end technical writer that never sleeps.

The Technical Workflow #

The core of this is a pipeline that turns raw machine-readable specs into human-friendly guides. If you have a basic grasp of Python, you can set this up in a few hours.

1. Extraction: You need the raw OpenAPI or Swagger spec. Most of these niche companies have a /openapi.json

file floating around that is barely touched.

import requests
from bs4 import BeautifulSoup

def fetch_openapi_spec(url):
 response = requests.get(url)
 return response.json() # Most APIs expose /openapi.json

2. Content Generation: This is where the prompt engineering comes in. You don't just ask the AI to "summarize"; you force it to provide concrete value like use cases and multi-language code snippets.

def generate_endpoint_doc(endpoint_data):
 prompt = f"""
 Write developer documentation for this API endpoint.
 Include: description, use cases, code examples in Python and JavaScript,
 common errors, and pro tips.
 
 Endpoint data: {endpoint_data}
 """
 return gpt4_response

3. Deployment: I use GitHub Actions to automate the regeneration. This ensures that if the API provider updates their spec, the docs refresh automatically without me touching a keyboard.

name: Regenerate Docs
on:
 schedule:
 - cron: '0 2 * * 1' # Every Monday at 2am
jobs:
 build:
 runs-on: ubuntu-latest
 steps:
 - name: Generate and deploy
 run: python generate_docs.py && npm run deploy

The Business Logic #

I've found that the "free sample" approach is the only way to close these deals. I pick one endpoint from their API, generate a beautiful, comprehensive guide, and send it over. The conversion rate is surprisingly high because you're showing them a finished product rather than promising a service.

For pricing, I avoid one-time fees and stick to subscriptions:

Starter:~$200/mo for one API with monthly updates.** Growth:~$400/mo for multiple APIs and weekly updates. Agency:**~$800/mo for white-labeling and unlimited endpoints.

Real-World Performance #

After running this for half a year, the numbers are incredibly lean. With four clients, I'm seeing about $847 in MRR. The monthly overhead—hosting and API credits—is roughly $45, meaning the net margin is nearly 95%.

The actual workload is negligible, maybe 3 hours a month for QA and emails. The reason it sticks is that once a company integrates your documentation into their developer onboarding, you become a critical part of their infrastructure. It's a classic "set it and forget it" AI workflow.

Next Can OpenAI actually make AGI affordable enough for every single →

a practical ChatGPT prompt guide, with plenty of directly applicable cases.