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Aleksei Mikhailov Available
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Technical specification (tech spec): how to write it without fluff and get a reliable estimate

If you google “technical specification”, “requirements template”, or “PRD/SRS example” - the reason is usually simple: you want a predictable timeline and budget, not “roughly 2-3 weeks” followed by endless extra work.

Below is a practical spec structure that teams actually read and that helps you:

  • make it clear what exactly must be built
  • get a realistic software timeline estimate and cost estimate with risks
  • avoid “we misunderstood” and rework

What a good spec is (in one sentence)

A good spec is a set of testable requirements: what must work, for whom, in which scenarios, what constraints exist (security/performance/integrations), and by which criteria we accept the work as done.

You don’t need a 40-page novel. You need clear and verifiable.

1) The shortest useful spec (when time is limited)

If you want to “assign a task to developers” quickly, the minimum is 9 blocks:

  1. Goal (business outcome)
  2. Users and roles
  3. Scenarios (step-by-step flows)
  4. Functional requirements
  5. Non-functional requirements (performance, security, load, SLA)
  6. Integrations (CRM, payments, external APIs, webhooks)
  7. Data (what is stored, what is PII)
  8. Analytics/events (what you measure)
  9. Acceptance criteria (how we verify “done”)

This is enough to move into estimation and a delivery plan.

2) Full tech spec structure (template)

This skeleton works for:

  • website or landing page
  • web app / dashboard / admin panel / internal CRM
  • mobile app (iOS/Android)
  • Telegram bot / chatbot
  • API integration (payments, CRM, delivery, etc.)

2.1. Context and goal

  • What business/process is this (1-2 paragraphs)
  • Primary goal (e.g. “increase qualified leads”, “reduce support load”, “automate payments”)
  • KPI (what counts as success)

Example wording:

  • “Goal: reduce request processing time from 15 minutes to 3 minutes via automation and templates.”

2.2. Scope and what we explicitly do NOT build

This is critical for budget control.

  • What is included in the first version (MVP)
  • What is not included (later / out of scope)

2.3. Users, roles, permissions

  • Roles (customer, admin, manager, operator, etc.)
  • Permissions matrix (who can see/do what)
  • Audit log requirements (if needed)

2.4. Scenarios (user stories) and states

List the key flows:

  • scenario steps
  • edge cases (cancel, retry, wrong input, network loss)
  • states (draft/pending/paid/failed, etc.)

2.5. Functional requirements (by modules)

Break down by modules:

  • onboarding/auth
  • payments/subscriptions
  • catalog/content
  • admin panel
  • notifications

2.6. Integrations

For each integration:

  • what system (CRM, payment provider, etc.)
  • events and webhooks
  • retry/idempotency requirements
  • rate limits and failure modes

2.7. Non-functional requirements

  • performance targets (TTFB, p95 response time)
  • expected load (users/month, RPS)
  • security requirements
  • backups and data retention

2.8. Data and compliance

  • what data is stored
  • what is PII
  • retention rules
  • access control

2.9. Acceptance criteria and definition of done

For every key scenario:

  • what “done” means
  • how we test/accept it

3) Spec nuances by project type

3.1. Spec for a Telegram bot

Add details:

  • bot UI states (menus, buttons, messages)
  • how you handle “Telegram limitations”
  • how payments work (provider, webhooks, retries, idempotency)
  • admin panel needs (pricing, content, users)

3.2. Spec for a mobile app

Add:

  • screens, navigation, states
  • offline requirements
  • OS-level permissions (camera, geo, etc.)
  • release constraints (App Store / Google Play)

3.3. Spec for a website/landing

Add:

  • pages list
  • SEO requirements (title/description, speed, schema if needed)
  • forms integration (CRM/Telegram)

3.4. Spec for a web app/dashboard/CRM

Add:

  • roles/permissions in detail
  • reports/exports
  • audit log of actions
  • performance requirements (lists/filters especially)

4) How a spec becomes an accurate estimate

A real estimate looks like:

  • module list
  • estimate per module (usually ranges)
  • assumptions and risks
  • “what if” deltas (e.g. “if roles/permissions are more complex -> +X”)

If you get a single number without risks and assumptions, that’s guessing, not estimation.

5) Common spec mistakes (and how to fix them)

  1. No scenarios -> add user stories and steps
  2. “fast/pretty/convenient” -> replace with measurable criteria
  3. Missing roles/permissions -> later admin/security rework
  4. Integrations described as “connect somehow” -> later weeks of debugging webhooks and failures
  5. No non-functional requirements -> “suddenly slow” in production

6) How I can help with your spec

Formats:

  • Idea -> spec (interviews + structure + scenarios + acceptance criteria)
  • Spec review and estimation (with risks, assumptions, work plan)
  • Spec + architecture + roadmap (so you can hire a team/vendor safely)

If you want, we can turn your idea into clear requirements and acceptance criteria so a team/vendor can estimate and ship without guesswork. To start, 3 bullets are enough: what you build and for whom; constraints/integrations; timeline/budget.

Free consultation