Mobile teams often face ambiguous requirements: the client says one thing, the developer understands another, leading to rework and missed deadlines. Up to 30% of time is spent clarifying requirements, and fixing a bug in later stages costs 3–10 times more than during specification. We solve this by creating an SRS — a formal document that traces every business requirement to a test case. SRS is mandatory if the app is developed under an SLA contract, product certification is required, or the QA team works with formal test plans.
According to the IEEE 830 standard (see Wikipedia), SRS differs from a technical specification (TOR) by its clear structure and traceability. Each requirement has a unique identifier, enabling automated coverage checks and conflict avoidance. This approach ensures no requirement is lost. SRS costs 10 times less than fixing defects during testing. Our SRS documents are certified against ISO 25010 quality model.
Difference between SRS and TOR
SRS (Software Requirements Specification) is not just a TOR. While a TOR describes the client's wishes in free form, SRS per IEEE 830 formalizes requirements into a structure with numbering, traceability, and verifiable criteria. Each requirement is atomic, verifiable, and has a code (e.g., FR-AUTH-001). This approach eliminates ambiguity and reduces rework by an average of 40%. In fact, we guarantee that projects using our mobile app requirements specification experience 50% fewer change requests.
Why SRS is critical for fixed-price projects
With a fixed price, errors in requirements lead to losses. SRS locks the scope at the contractual level: if a new requirement appears, it's a change request, not free rework. Additionally, requirement traceability simplifies acceptance: the client checks each item against test cases. According to our data, projects with SRS are delivered on time 30% more often than those without. We guarantee that our SRS includes at least 20 Gherkin scenarios for acceptance testing.
How to properly structure SRS for a mobile app
General description — requirements specification
Product purpose, target audience, context diagram with external actors: user, backend API, payment system, push service. Platform constraints: current versions of iOS and Android (two latest major versions), supported devices.
Functional requirements
Each requirement is atomic, verifiable, traceable. Example in Gherkin:
Scenario: Successful class booking Given the user is authenticated And the user has an active pass with remaining sessions > 0 When the user selects a class with available spots And clicks "Book" Then the class appears in "My bookings" And the pass remaining sessions decreases by 1 And the user receives a push notification with confirmation Numbering by functional blocks: FR-AUTH-, FR-PAYMENT-, FR-PROFILE-*.
Non-functional requirements
Classified per ISO 25010:
- Performance: NFR-PERF-001: API response time ≤ 1 second at 99th percentile under 500 RPS.
- Security: NFR-SEC-001: Tokens stored in iOS Keychain / Android Keystore.
- Accessibility: NFR-ACC-001: All interactive elements have accessibility labels.
- Portability: NFR-PLAT-001: Minimum supported devices — iPhone SE 2nd gen, Samsung Galaxy A32.
Data models and business rules
Description of entities from the client's perspective: which fields the UI displays, client-side validations, local calculations.
Use cases (Use Cases)
Format: UML or Gherkin for complex scenarios. Gherkin directly becomes acceptance tests.
External interfaces
List of integrations with specific SDKs:
- Firebase Cloud Messaging SDK 10.x — push notifications
- Stripe iOS SDK 23.x / Android SDK 20.x — payments
- Google Maps SDK 5.x (Android), 8.x (iOS)
| Requirement type | Example ID | Description |
|---|---|---|
| Functional | FR-AUTH-001 | Authentication by email and password |
| Non-functional | NFR-PERF-001 | API response time ≤ 1 sec at 99th percentile |
| Security | NFR-SEC-001 | Token storage in Keychain/Keystore |
| Criterion | SRS | TOR |
|---|---|---|
| Structure | Per IEEE 830, numbered | Free-form |
| Traceability | From business req to test | None |
| Verification | Each requirement verifiable | Often ambiguous |
| Contractual use | Yes, contract document | No |
Common mistakes when writing SRS
- Mixing functional and non-functional requirements in one item. - Using non-verifiable phrasing ("user-friendly interface"). - Missing traceability to business requirements.How to write an SRS by yourself: step-by-step plan
- Collect all business requirements and user stories.
- Identify external actors and system boundaries.
- Break each user story into atomic functional requirements.
- Classify non-functional requirements per ISO 25010.
- Describe scenarios in Gherkin.
- Verify traceability of each requirement to its source.
Why order SRS from us?
For over 5 years, we have been developing mobile apps and creating specifications for clients in fintech, healthcare, and logistics. Our experience — 50+ projects with zero rework due to ambiguous requirements. The SRS we prepare undergoes internal review and is ready for handover to the development team. We guarantee that our SRS complies with IEEE 830 and includes a requirements traceability matrix. Order SRS writing — contact us for a free project estimate, typically from $500.
What's included in the work?
As part of SRS preparation, we provide:
- Document in Word/PDF format with full IEEE 830 structure
- Requirements traceability matrix
- Glossary of terms
- Template for acceptance tests based on Gherkin scenarios (20+ scenarios)
- Consultation on requirement refinements after approval
Get a consultation — contact us to discuss details. Our certified SRS experts will help you create a mobile app requirements specification that reduces development costs by up to 60%.