A good side income fits what you already have: free time, a particular skill or some capital. If you're honest with yourself about that first, you'll avoid most false starts. In this article we compare the common models by what they really demand, not by what adverts promise.
In brief
A side income is money you earn on top of your main job. Which model suits you depends on what you bring: free time (e.g. a mini-job), a skill (e.g. freelancing) or capital (e.g. ETFs or machines such as powerbank stations). Models that use capital need the least ongoing time.
Contents
What actually counts as a side income?
A side income is any income alongside your main job, whether from work, capital or a small business of your own. For tax purposes it's usually nothing special: in Germany, anything above the tax-free allowances is taxed as normal. We explain exactly how that works in a separate article.
What kinds of side income are there, and what do they demand?
| Model | Time required | Start-up capital | Risk | How scalable |
|---|---|---|---|---|
| Mini-job | high, fixed and plannable | none | very low | barely, hours are limited |
| Freelancing (writing, design, IT) | medium to high | low | low | limited by your own time |
| Online shop / dropshipping | high, especially at the start | medium | medium to high | good, but with a lot of competition |
| Content, blog, affiliate | high, months without income | low | medium | good, if you build an audience |
| ETFs and dividends | low | high, to earn noticeable returns | depends on the market | good, but slow |
| Renting out (room, parking space, equipment) | low to medium | depends on the asset | low to medium | limited by the asset |
| Snack or drinks machines | medium (restocking, stock, cleaning) | medium | medium | good |
| Powerbank sharing stations | low in day-to-day running, higher when finding locations | from approx. €1,500 | medium, depends on the location | good |
Which side income suits whom?
If you mainly have time: a mini-job or freelancing. Both bring in money from the first month, but stop as soon as you stop working. In Germany, a mini-job is free of tax and social security deductions for you as an employee up to €603 a month in 2026.
If you have a skill: freelancing or content. Here the money lies in your own know-how. The downside: your time remains the bottleneck, and with content it often takes a year before meaningful income comes in.
If you have capital but little time: ETFs, renting out or a small vending business. ETFs are the most convenient, but with small amounts they hardly produce a noticeable monthly income. Machines sit in between: you buy a device, set it up in a good place and earn every time it's used. But it doesn't work entirely without effort either, because you have to find and look after the location.
Why machines are becoming more popular as a side income
Machines have an advantage most other models don't: they keep selling while you're at your main job. At the same time it's a real business with customers, costs and a location, not a financial product. Classic snack machines need regular restocking. Newer models such as powerbank stations don't need refilling, because the "product" is returned and recharged in the station. You'll find the direct comparison here.
Why powerbank sharing appeals to many people
Almost everyone knows the situation: your battery is flat and you're at a club, a bar, a hotel or a hospital. In many Asian countries and parts of Europe, you'd simply rent a powerbank from a station. In Germany that's still rare. So if you set up a station in a good place today, you're entering a market that is only just emerging here.
The model fits a side income for three reasons:
- Little ongoing effort: the station runs automatically, and payment and billing are digital. There's no stock that goes off or needs restocking.
- A manageable start: you can start with a single station and expand once it proves itself.
- The location makes the difference: if you have contacts in hospitality or the events industry, you have a real advantage.
To be just as honest: a station at a poor location earns little. And if you only want to invest money without looking after anything, an ETF will serve you better. We work out what a station realistically earns using real numbers.
Frequently asked questions
Which side income is the safest?
A mini-job or freelancing in a field you know well. Neither needs capital, so you only risk your time.
Is there a side income with no effort at all?
No. Even with ETFs or machines you have to get to grips with things, at least at the start. Anyone promising "money without work" is usually selling something else.
How much start-up capital do I need for a side income?
None for a mini-job or freelancing, usually a few hundred to a few thousand euros for an online shop, and from around €1,500 for a powerbank station.
Thinking about starting with your own station?