Technical Documentation in Software Projects: What to Write and How to Keep It Alive

Software without documentation depends on the memory of whoever wrote it. For an SME the risk is real: when a developer or supplier changes, knowledge is lost and everything slows down. A few well-chosen documents, such as READMEs, ADRs and runbooks, are enough to cut the risk without weighing projects down.

Why Documenting Pays Off

Documentation shortens onboarding, reduces dependence on individuals, eases handover between suppliers and speeds up responses when something breaks. It also surfaces in technical due diligence for acquisitions or security audits. Written as you work, the cost is minimal compared with rebuilding the information afterwards.

The Essential Documents

• README: what the project is, how to install, start and test it, who to contact.
• Architecture: a simple diagram of components, data flows and external integrations.
• ADR (Architecture Decision Record): a short note recording a technical decision, its context and the alternatives rejected.
• Runbook: step-by-step operating instructions for deployment, recovery, credential rotation and incident handling.
• User manual and FAQ: a guide for people who use the software every day.

ADRs: Remembering the Why

Code shows what the system does, not why that database or supplier was chosen. An ADR is a page with title, date, context, decision and consequences. Written at the time of the choice, it avoids reopening the same questions months later and explains a trade-off to newcomers.

Runbooks: Acting Well Under Pressure

In an emergency there is no time to remember. A runbook lists the steps, commands, verification checks and contacts. Test it periodically, for example with a backup restore on a test environment, and fix it where the steps do not work.

Keeping It Up to Date

• Keep documents close to the code, in the same repository, and review them in the same change requests.
• Include updating documentation in each task's definition of done.
• Assign an owner to each document and a periodic review, for example every quarter.
• Prefer short, concrete texts to long manuals nobody updates.

What to Ask Suppliers

In development contracts, provide for delivery of documentation, source code and environment access as part of the result, not as extras. At project close, verify that an outside technician can start the system using only the documents.

Key takeaway: a few essential documents, written as you work and kept close to the code, turn the knowledge of a few people into a company asset and make software projects safer, more transferable and cheaper to run.