Latest / The Side Hustle Career Podcast with Fexingo: Second Income, Freelancing While Employed / How a Software Engineer Built a 12K Monthly Side Hustle in API Documentation
Transcript
- Lucas: Alright, let's talk about a side hustle that sits right at the intersection of technical skill and clear communication — API documentation. You might not think of writing docs as a lucrative gig, but one software engineer we spoke to is pulling in about twelve thousand dollars a month doing exactly that. Luna: That's a serious number. And honestly, anyone who's ever tried to use a poorly documented API knows exactly how much frustration exists in the market. So who is this person? Lucas: Her name is Priya, she's a backend engineer at a mid-size fintech company in Austin. She started freelancing about two years ago after she spent a weekend untangling a third-party API's docs for a project at work. She thought, 'If I'm struggling with this, other developers must be too.' And she was right. Luna: So she basically turned a pain point into a service. What did she do first? Lucas: She started small. She reached out to a few startups she found on AngelList that had public APIs but zero documentation — or just a README file with a few endpoints listed. She offered to write a complete documentation set for a flat fee. Her first project was for a small SaaS company making inventory management software. She charged two thousand dollars for an initial docs package covering about fifteen endpoints. Luna: Two grand for what probably took her a weekend? That's a solid hourly rate. Did she have to learn any new tools? Lucas: She was already comfortable with Markdown and Git, so the learning curve was mostly around documentation-specific tools like ReadMe.io and Stoplight. She also picked up OpenAPI spec — which is the standard for describing RESTful APIs. Those are all pretty accessible if you're already a developer. Luna: And that's the key, right? She's not just writing prose — she's writing accurate, testable documentation. She can actually verify that the code samples work. That's way more valuable than what a general technical writer could produce. Lucas: Exactly. Her engineering background is her competitive advantage. She tells us that clients often say they've hired technical writers before, but the docs were either too high-level or contained code that didn't compile. Priya tests every snippet herself. Luna: So how does she find clients now? Is she still cold-emailing? Lucas: Not anymore. After her first few projects, she built a simple portfolio site showcasing anonymized samples. Then she started getting referrals. She also contributes to open-source API doc projects — like the Stripe docs and Twilio's — which gives her visibility. Now, about seventy percent of her work comes from inbound inquiries. Luna: I love that she gives back to the community and it pays off. What does her typical project look like in terms of scope and pricing? Lucas: Her rates have scaled. For a new client with a moderate API — say twenty to thirty endpoints — she charges between four and six thousand dollars for a full documentation suite, including an interactive reference, a getting-started guide, and code samples in three languages. She also offers a maintenance retainer for four hundred dollars a month to keep docs up to date as the API evolves. Luna: That retainer is smart. It's recurring revenue, and it keeps her engaged with the product. So she's not constantly hunting for new projects. Lucas: Right. She now has five retainer clients, which gives her a base of two thousand dollars per month before she even takes on new projects. The remaining ten thousand comes from one-off documentation projects, which she might do two or three of per month. She's actually turned down work because she doesn't want to exceed about twenty hours a week on the side hustle. Luna: And that's a good note — she's still working her full-time job. How does her employer handle this? Lucas: She's very careful. Before starting, she reviewed her employment contract and spoke with her manager. Her company allows outside freelance work as long as it's not with direct competitors and doesn't use company resources. She also uses a separate laptop for freelance projects and never works on them during business hours. Luna: That's smart. And it shows respect for her day job. If today was actually useful to you, the way these stay ad-free is listener support — buy me a coffee dot com slash fexingo. It's a small way to keep conversations like this going without any sponsored interruptions. Lucas: Yeah, absolutely. And we genuinely appreciate that. So back to Priya's story — one thing I found interesting is how she handles scope creep. Because APIs change, and clients sometimes expect unlimited updates. Luna: How does she set boundaries? Lucas: She has a very clear contract. The initial project includes one round of revisions after delivery. Any additional changes — like new endpoints added during development — are billed hourly at one hundred and fifty dollars per hour. She says this has saved her from a few nightmare situations where clients kept asking for tweaks months later. Luna: One fifty an hour is solid. And I imagine that keeps clients from being casual with change requests. Lucas: It does. And it also means she's earning well for any extra work. But I think the bigger lesson here is that this is a side hustle that leverages a skill you already have. You don't need to learn a completely new trade. If you're a developer, you already understand APIs, you already write code, you already know what good documentation looks like. You're just packaging that knowledge. Luna: And the demand is real. I checked — there are job boards specifically for API technical writers, and companies like Google, Stripe, and Twilio are constantly hiring for this. But freelancing gives you more control. Lucas: Right. Priya's story also shows that you don't need to be a senior engineer to do this. She was about three years into her career when she started. What she had was empathy for the developer using the API. That's the real skill. Luna: So if someone listening is a software engineer or even a technical product manager, what's the first step you'd recommend? Lucas: Pick one existing API you use regularly — maybe a popular one like the GitHub API or the Notion API. Write a sample documentation section for a part of it that you think is poorly explained. That becomes your portfolio piece. Then find three startups with public APIs that lack clear docs and send a personalized email offering to write a getting-started guide for free or at a discount. Prove your value, then raise your rates. Luna: Start small, get a testimonial, then scale. That's the pattern we see across so many side hustles. And Priya's story is a great example of how technical skills can be monetized in a non-obvious way. Lucas: Definitely. And if you're interested, we'll put a link to her portfolio and a template for the kind of email she used in the show notes. Next week, we'll look at a totally different angle — how a kindergarten teacher built a side hustle selling lesson plans on Teachers Pay Teachers. That one's a different kind of documentation, but equally lucrative. Luna: Looking forward to it. Thanks for listening, and if you found this useful, remember — buy me a coffee dot com slash fexingo.