If you asked me the single biggest reason a software project doubles its timeline or gets cancelled, I wouldn't say "hard technology" or "weak developers." It's almost always this: both sides understood one word in two different ways, and discovered it two months in.
The problem in one sentence
The client says: "I want an order management system." In their head: a screen with orders, a notification when one arrives, and a month-end report. In the developer's head: an orders table and an add screen. Both agreed, and both understood completely different things.
The spec document is where you discover that gap before anyone spends money.
What belongs in the spec
1. The list of users and their permissions. Who logs in? Manager, salesperson, accountant, external client? And exactly what does each see and do? That table alone exposes half the hidden complexity.
2. Every process, step by step. Not "order management," but: "the salesperson opens a new order screen, picks a customer from a list or adds a new one, adds items, the system applies a discount automatically based on customer tier, saves as draft or confirms, and on confirmation the warehouse is notified and stock is deducted."
Every sentence like that saves a day of arguing later.
3. Edge cases. What happens if stock is insufficient? If the customer has overdue debt? If an order is cancelled after shipping? These surface at the end of a project and blow up the schedule.
4. Reports, by name. "Reports" is elastic. Write: monthly sales by item, stock balance report, customer statement. And define what each one filters by.
5. External integrations. Payment gateway? Shipping company? An existing accounting system? WhatsApp? Each integration is a small project inside the project and must be priced separately.
6. What is out of scope. This is more important than the item before it. State plainly: "the mobile app is not part of this phase," "migration from the old system is not included." It protects both sides.
Questions to ask a software company before signing
- Will the code be mine? When and how do I receive it? - If your team changes, is the documentation enough for someone else to continue? - Is delivery phased? What is in each phase and when? - How long is the warranty after delivery, and what is in and out of it? - How are out-of-scope changes priced — hourly or per task? - Where will this be hosted, and can I move it if I want?
A serious company answers all of this in writing without getting defensive. One that talks around the answer is a warning sign.
The common client mistake: "I'm not technical, you're the experts"
True, you don't need to know the technology. But you're the only one who knows your business. The best specs are written collaboratively: you describe the process in your language, the company converts it into a technical spec and hands it back for review.
If a company tells you "we don't need a spec, we understand" — that's not confidence, it's a risk you'll pay for.
Bottom line
An extra day of specification saves a week of building. Write the users, the journeys, the edge cases, the reports and the out-of-scope list. And if you don't know where to start, we run an analysis session that produces a complete spec you can take to any company — even if it isn't us.