Side hustle for engineers: 7 options compared, and which to try first
Seven side hustles for software, mechanical, electrical and civil engineers compared on pay, time and employer conflict risk, with the one to try first.
The best side hustle for engineers to try first is paid expert calls about the tools, vendors and equipment you already use, because one call takes an hour, needs no setup and pays a rate you set. Freelance contracts, technical writing, tutoring, open source sponsorships, small products and startup advising all work too, but each one costs more hours or carries more risk under your employment contract.
This post compares all seven for software engineers and for mechanical, electrical and civil engineers, then says which to try in what order.
1. Price your evenings against your salary first
A side hustle should pay more per hour than your day job, because it comes out of your free time. The US Bureau of Labor Statistics puts the May 2025 median annual wage for software developers at $135,980. For other engineers, the architecture and engineering occupations page lists $125,040 for electrical and electronics engineers, $104,110 for mechanical engineers and $100,840 for civil engineers.
By our arithmetic, the software figure divided by 2,080 working hours is about $65 an hour, and that hour also came with paid leave and health insurance. An option that pays less per hour needs a reason other than money, such as reputation or enjoyment. The consulting side hustle guide works through pricing and tax on side income.
2. Read the invention assignment clause before you write a line of side code
Engineers carry a risk most side earners don't: the thing you make may already belong to your employer, because many engineering offer letters include an invention assignment clause.
A few states limit these clauses. California's Labor Code section 2870 and Washington's RCW 49.44.140 protect inventions you make entirely on your own time without the employer's equipment, supplies, facilities or trade secrets. Both keep the exception that matters most: the employer can still claim an invention that relates to its business or research, or that comes from work you did for it.
So a payroll engineer building a payroll tool on weekends is in the riskiest spot, even on a personal laptop. A firmware engineer writing a woodworking blog is not. The post on moonlighting policies covers how to read your employer's rules and ask for approval. This is not legal advice; for anything you plan to sell, a short call with an employment lawyer costs less than a dispute.
3. Compare the seven options on pay, time and conflict risk
| Option | What it pays (sourced where possible) | Time shape | Main conflict risk |
|---|---|---|---|
| Paid expert calls | A rate you set | One call, often booked within days | Confidential information |
| Freelance or contract work | Your rate, minus a platform fee of 0% to 15% on Upwork | Weeks, on the client's deadlines | IP assignment, competing work |
| Technical writing | $300 to $400 per tutorial in one public program | A few evenings per piece | Low, if you skip employer internals |
| Tutoring and teaching | Median tutor pay is well below an engineer's | Fixed weekly slots | Low |
| Open source sponsorships | Whatever sponsors give, with no GitHub fee from personal accounts | Ongoing maintenance | IP assignment |
| Small products | Sales, minus store or payment fees | Months before the first sale | IP assignment, highest |
| Advising startups | Usually equity | A meeting a month, plus messages | Competitors, time creep |
The sections below fill in each row.
4. Start with paid expert calls, because buyers want people who use the tools
Investors studying a software or industrial company, and vendors planning a product, pay to hear from the people who buy and run that product every day. An engineer who chose between two observability tools last quarter, or who specified the pumps on a water treatment job, has exactly the view they want.
The pay is set by you. GLG's network members page says you set your own rate, get paid after the project at that rate, and that the faster you respond, the more likely you are to be selected. Guidepoint's advisor page asks for 10+ years of experience, says each invitation states the scope, time and pay up front, and notes that consultations are often completed within 72 hours of the first request.
Here is a made-up example. Priya is a staff engineer at a freight company who led her team's move from one CI vendor to another last spring. An investor asks for an hour on how her team compared the two, what broke during the move and what the bill looked like a year later. Priya can answer all of it from her own experience without naming her employer's numbers.
The risk is confidential information. GLG's compliance page says employed experts are barred from projects about their own employer. In 2011 the SEC charged a hedge fund and traders in a case built on tips from "technology company employees moonlighting as expert network consultants". Talk about your experience as a user and buyer. Never talk about your employer's unreleased products, customers or results. The post on material non-public information explains where the line sits, and expert network calls covers what happens on one.
5. Take freelance contracts only when the scope is tight
Freelance work takes the most of your weeks, and you compete with full-time freelancers who can take a call at 10am.
Upwork's freelancer service fee ranges from 0% to 15% per contract and is shown before you send a proposal. Price with the fee in mind, and pick fixed-scope work with a written deliverable. Open-ended hourly contracts tend to want you during your day job's hours.
Contract code is also where the IP clause bites hardest. Never take a client in your employer's line of business.
6. Write technical tutorials for reputation first and money second
Technical writing pays per piece, and a good piece stays public long after you are paid. DigitalOcean's Write for DOnations program pays $300 to $400 per published tutorial (the page gives both figures and says payouts are at editorial discretion), plus a $25 donation to a tech charity you pick. Tutorials there are published under a Creative Commons noncommercial license, so you give up exclusive rights to them.
For context, BLS reports a May 2025 median of $43.46 an hour for technical writers. By our arithmetic, a tutorial that takes you 20 hours pays $15 to $20 an hour. Write when the topic is one you would explain anyway, and let the article be the reason a buyer or recruiter picks you later.
7. Tutor or teach only if you enjoy it
Tutoring is easy to start and pays the least of the seven. The BLS median for tutors was $20.84 an hour in May 2025, and most tutors work part time. An engineer can charge more for advanced material, but the market sets the anchor. Teach because you like it, or because explaining things makes you better at them.
8. Treat open source sponsorship as a tip jar for work you already do
GitHub Sponsors takes no fee on sponsorships from personal accounts and up to 6% on sponsorships from organizations. That is a generous deal, but sponsors pay for projects people already depend on. Maintaining one is ongoing work with no fixed end.
Check your contract before you open a sponsors page. Code in your employer's field can fall under the assignment clause even when it is open source.
9. Build a small product last, after the IP question is answered
A small app, plugin or tool can earn without your time once it is built. Apple's App Store Small Business Program charges a 15% commission for developers with no more than $1 million in proceeds a year, so the store fee is clear. The time to the first sale is not, and nobody can promise it will arrive.
This option has the highest IP risk, because a product is an invention. Get written approval or a clear legal answer before you start, not after you have users.
10. Advise a startup when you would answer their questions for free anyway
Advising pays mostly in equity, which may never be worth anything. The post on startup advisor compensation covers typical grants. Advise a company in a field next to yours, never a competitor or a vendor your team buys from, and cap the hours in writing.
Our order: calls, then writing, then everything else
Start with paid expert calls, since they need nothing built in advance and you can turn down any request. Add technical writing next if you want a public reputation. Leave products and contract code until your employer has said yes in writing.
For a broader comparison of paid advice formats, see get paid to give advice. To see how other engineers are listed, browse engineering professionals in developer tools or in enterprise SaaS.
On Instant Expert, a buyer invites you to a specific paid call or a written or voice answer and sets the amount up front; you receive the full amount, or you can reply with a higher price. Claim your profile to set the rate buyers start from, or see open paid requests on the request board.