Phase 3 - High-Fidelity Prototype Development
After the product structure is validated through Information Architecture, Design System, and User Flows, the next stage is to build a High-Fidelity Prototype (HiFi Prototype). In this phase, the product concept begins to be realized into a visual representation that resembles the actual application, complete with layout, navigation, and user interactions.
The main goal of this phase is to validate the user experience before the team starts writing code. With a prototype, stakeholders can see and try the system flow in a tangible way so that usability, navigation, or business process issues can be discovered early.
What is Built?
A High-Fidelity Prototype typically includes:
- Page layout
- Page navigation
- Form inputs
- UI Components
- State and system feedback
- Form validation
- Error messages
- Responsive behavior
- User interactions
The prototype is developed based on three previous Sources of Truth:
- SoT #2 — Information Architecture
- SoT #3 — Design System
- SoT #4 — User Flows
Thus, the design is not created based on assumptions or creativity alone, but based on validated needs and flows.
Why is a Prototype Important?
Many product errors actually originate not from code, but from incorrect process design and user experience. If problems are only discovered after implementation, the cost of fixing them is much higher.
A High-Fidelity Prototype allows the team to:
- Validate user needs
- Validate business flows
- Test usability
- Get stakeholder feedback
- Reduce revisions during implementation
Prototype Validation
The prototype must be reviewed by stakeholders before becoming a Source of Truth.
Some questions that need to be answered:
- Are the user flows correct?
- Is the navigation easy to understand?
- Is the information displayed correctly?
- Are all acceptance criteria accommodated?
- Are there any unnecessary or confusing steps?
If problems are found, fixes are made to the source artifacts. For example, if the user flow is wrong, the User Flow must be revised first before the prototype is updated. This principle maintains consistency between artifacts in the Chain of Truth.
Output of Phase 3
This phase produces:
| Source of Truth | Description |
|---|---|
| SoT #5 | Validated High-Fidelity Prototype |
The validated prototype becomes the main reference for frontend implementation, user acceptance review, and application interface development.
Key Principle of Phase 3
This phase aims to ensure that the team builds the right product before starting to build that product with code. By validating the user experience early, the risk of major revisions during implementation can be significantly reduced.