What Is a Technical Specification? | Vantage
Technical Specification A technical specification (tech spec) is a document that describes how a feature will be implemented at the technical level: architecture decisions, data model changes, API design, and implementation approach. While a PRD describes what to build and why, the tech spec describes how to build it.
Why technical specification matters
Tech specs reduce implementation risk by surfacing technical challenges before coding begins. They create shared understanding between engineers, catch design flaws early, and serve as documentation for future maintainers. Skipping tech specs leads to ad-hoc architecture and inconsistent implementation.
How it works
The engineering lead writes the tech spec after the PRD is approved. It covers: proposed architecture, data model changes, API endpoints, migration plan, performance considerations, security implications, and testing strategy. The tech spec is reviewed by senior engineers and the PM before implementation begins.
Common mistakes
Writing tech specs for every feature (only features with significant technical complexity need them)
Tech specs that are disconnected from the PRD (they should reference requirements)
Over-specifying implementation details (describe the approach, not every line of code)
Not updating tech specs when the approach changes during implementation
PMs writing tech specs (the engineering lead should own the technical approach)
Related terms
How Vantage relates
Vantage connects to your GitHub codebase, so AI-generated PRDs reference your actual architecture. This provides context for the engineering lead writing the tech spec: the PRD already reflects technical constraints, reducing the gap between product requirements and technical design.