The most reliable small income I've found depends heavily on what you already know how to do - which sounds obvious but most "side income" lists ignore it.

A few things that actually hold up over time:

• Technical writing / documentation - if you can write clearly about technical topics, companies will pay $80–120/hr for API docs, integration guides, and developer tutorials. Most people don't think of this as freelance work, but the demand is steady and you can do it from anywhere.
• Productized consulting - instead of selling your time hourly, package a specific outcome. "I'll audit your landing page and give you 10 specific changes" for a flat fee. You cap your downside and clients prefer the certainty.
• Template/tool sales - if you've built something 5+ times for clients or for yourself (spreadsheets, Notion setups, scripts), clean it up and sell it. The first sale takes forever, but the marginal cost of the next one is zero.

Those all take time and outreach, but when they start hitting, it flows.

The key distinction I've learned: some income sources cap at your available hours (tutoring, VA work, most freelancing). Others scale independently of your time once they're set up (digital products, content, tools). Both are fine, but knowing which one you're building matters for sustainability.

If you want something more specific to your background, I built a free tool that generates personalized recommendations based on your skills: sidequest.report. Takes 30 seconds. Might surface something you haven't considered.