What is Technical Specification (Tech Spec / RFC)?
A technical specification (tech spec) or Request for Comments (RFC) is a document that describes the design of a system, feature, or architectural change before implementation begins.
A technical specification (tech spec) or Request for Comments (RFC) is a document that describes the design of a system, feature, or architectural change before implementation begins. It's the engineering equivalent of "measure twice, cut once."
A good tech spec includes: problem statement, proposed solution, alternative approaches considered and why rejected, API design, data model changes, migration plan, rollback strategy, security considerations, performance expectations, and testing plan.
Tech specs serve multiple purposes: they force the author to think through edge cases before coding, they enable asynchronous review from senior engineers, they create documentation that outlives the implementation, and they prevent the "build first, design later" anti-pattern.
Google, Netflix, and Uber require tech specs (or RFCs) for any change that affects multiple teams, introduces new dependencies, or modifies public APIs. The investment in upfront design pays back 5-10x in reduced rework.
Why It Matters
Tech specs prevent expensive rework by catching design problems before code is written. A design problem found in review costs 1 hour. The same problem found in production costs 10-100 hours to fix.
Frequently Asked Questions
What is a tech spec?
A document describing the design of a system or feature before implementation. It covers problem statement, proposed solution, alternatives, APIs, data models, and testing plans.
When should you write a tech spec?
For any change that: affects multiple teams, introduces new dependencies, modifies public APIs, changes data models, or takes more than 1 sprint to implement.
Related Terms
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