Answers
How do you check the code and tech stack before buying a small SaaS?
Short answer: Ask for read access to the code repository, a list of every service the product runs on and what each costs, and a written deploy process. Have someone set it up and deploy it from scratch before closing. Price any rewrite, upgrade or missing knowledge as a cost, and hold back part of the price until the handover is done.
What should you ask the seller for?
- Read access to the code repository, with its history, not a zip file sent the week before closing.
- A list of every service the product runs on: hosting, database, email sending, payments, storage, AI or other APIs, monitoring and domains, with the monthly cost and whose account each one sits in.
- A written deploy process: how a change goes from the code to the live product, and where the passwords, keys and settings live.
- Known issues: open bugs, outdated frameworks or libraries, and anything the seller has been meaning to rewrite.
- Who has written the code: the founder alone, contractors, or code generated with AI tools and not reviewed.
How do you check it runs without the founder?
The most useful test is simple. Before closing, have a developer you trust set the product up from the repository on a fresh account and deploy a small change, using only the seller's written notes. If it takes days of calls with the founder, that knowledge is part of what you are buying and needs to be in the handover. See how long the handover should be.
Also check which accounts move to you. A product on the founder's personal cloud account, or on an API key tied to their name, needs a migration plan, not just a password change.
What are the red flags?
- No repository history, or a repository created just for the sale.
- One outside service the product cannot work without, such as a single AI or data API with no fallback, which works like platform risk; see depends on one platform.
- Major frameworks several versions behind, or libraries that no longer get security fixes.
- Hosting costs well below what the usage suggests, which can mean free credits or a legacy plan that will end for a new owner.
- "Fully automated" in the listing but manual steps in the deploy notes; see described as fully automated.
What does a composite check look like?
This is a composite example, not a real deal. A small SaaS lists $3,000 a month in profit, asking $90,000. The code review finds it runs on startup credits worth about $400 a month that end at transfer, and its main framework needs an upgrade that a contractor quotes at about $6,000. The buyer restates profit at $2,600 a month, which at the same multiple is about $78,000, then takes the $6,000 upgrade off as well and offers about $72,000, with $7,000 held back until a fresh deploy works without the founder.
Run the listing through the free red-flag checker first, then work through the small SaaS due diligence checklist.
Frequently asked questions
Do I need to be a developer to buy a SaaS?
No, but someone who can read and deploy the code should check it before you close. A few hours of a contractor's time is small next to the price of a product that will not run without its founder.
Is code written with AI tools a problem?
Not in itself. The question is whether it is understood, tested and documented well enough for the next person to change it safely. The fresh deploy test answers that.
When should the code review happen?
After the LOI and before closing, usually under a confidentiality agreement. Before an LOI, ask for the service list and costs, which is enough to spot the biggest issues.
Sources
- FirstPass Memo, red-flag checker rules, our own rules, published as /rules.json
- FirstPass Memo, seller question bank, October 2026 (general checklist), our own questions
- FirstPass Memo, free buyer calculators, our own calculators; the formulas are on each page
Related
- Free red-flag checker
- Small SaaS due diligence checklist
- Red flags when buying a SaaS
- Questions to ask a SaaS seller before an LOI
- How long the handover should be
- Hidden costs of buying a website
- Red flag: depends on one platform
- Red flag: described as fully automated
- Glossary of listing terms
- More questions buyers ask
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Composite examples are invented and labelled. Figures from other sites are quoted with a link and the date we read them; FirstPass figures are asking prices and seller-stated profit, not sale prices. Informational screening only, not investment, legal or tax advice.