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Turn ideas into
engineering‑
ready specs.

Describe your product in five fields. limn returns a complete engineering spec — functional requirements, risk log, constraints, and open questions — in under two minutes.

Generate your first spec — it's free

No credit card  ·  3 free specs, no limit on time  ·  Ready in under 2 minutes

Not sure what you're building yet? Start with a PRD instead.

limn is building toward a complete engineering documentation platform

Spec generatorDocument suiteExecution bridgeTeam platform

How it works

Three steps. One engineering‑ready spec.

From rough idea to structured document in the time it takes to make a coffee.

01  ·  Input

Describe your product

Five fields: what you’re building, who it’s for, your constraints, what success looks like, and what’s already decided. No template. Rough notes work.

Generate a spec
Answer five questions.
What are you building?
A GPS route tracker for dog walkers, so owners can record and share walks…
Who are your primary users?
Dog owners, urban. 1–2 dogs daily…
What are your constraints?
No budget for paid APIs. Solo dev. iOS first.
What does success look like?
500 MAU within 90 days.
What’s already decided?
React Native, Supabase.
02  ·  Infer

limn thinks like an engineer

It completes a full spec, including requirements you didn’t think to specify, alongside a risk log, constraints, and prioritised open questions. Every assumption is flagged.

Walker Tracker: Design Specification
Generated in 18s
2. Functional Requirements
FR-01Track GPS at 10-second intervals during active walks.
FR-02Cache last known location locally when offline and sync on reconnection.inferred
FR-04Display a live GPS polyline on the map view for each active walk session.inferred
FR-09Provide account deletion flow compliant with GDPR and App Store rules.inferred
03  ·  Ship

Ready for engineering

Export as PDF, copy as markdown, or share a link. Engineers receive a structured document they can act on without a follow-up meeting.

Walker Tracker: Design Specification
Generated 15 June 2026 · limn
§1
Product overview
A GPS route tracker for dog walkers…
§2
Functional requirements
21 requirements · 7 inferred
§3
Constraints
7 constraints · 7 assumptions
§4
Success criteria
7 criteria across Technical, UX, Business
§5
Risk log
7 risks · High to Low
§6
Open questions
7 questions · 2 Critical · 5 High
Generate a spec
Answer five questions.
What are you building?
Who are your primary users?
Dog owners, urban. 1–2 dogs daily…
What are your constraints?
No budget for paid APIs. Solo dev. iOS first.
What does success look like?
500 MAU within 90 days.
What’s already decided?
React Native, Supabase.

The signature feature

The requirements your
engineers find in week three.

When you describe your product, limn infers the requirements you didn't think to write — auth flows, error states, data retention, GDPR account deletion, background GPS battery considerations. These are the things your engineers discover in sprint three. limn surfaces them in your spec on day one.

Generate your first spec — it's free

What you get

Every section. Every edge case.
Every time.

§1Product overview
3–5 sentence synthesis of what you're building and the core value proposition.
§2Functional requirements
8–20 "The system shall…" requirements grouped by feature area. A minimum of 5 inferred requirements are included in every spec.
§3Constraints & assumptions
Hard constraints listed clearly. Every assumption flagged with its risk — including spec-invalidating ones.
§4Success criteria
A table with measurable targets across Technical, UX, and Business outcome dimensions.
§5Risk log
5–8 risks with deliberate likelihood, impact, and specific actionable mitigations, sorted by priority.
§6Open questions
6–7 prioritised questions — Critical or High only — identifying exactly what blocks work starting and who needs to answer them.

Features

Edit, iterate, and refine. Without starting over.

Every spec is a living document. limn gives you the tools to refine it as your understanding grows.

EDIT AND DELETE

Refine any requirement directly

Hover any item to reveal Edit and Delete. Double-tap to go straight to edit mode. Two-step delete confirmation prevents accidents.

Walker Tracker: Design Specification
Generated 12 June 2026 · limn
Copy spec

Functional requirements

GPS tracking

Deep dive

FR-01: Track GPS at 10-second intervals.

FR-02: Cache location when offline.inferred

EditDelete
Sync location queue on reconnection.
⌘↵ save · Esc cancelCancelDeleteSave

FR-04: Display live polyline on the map.inferred

62 / 100

Hand-written spec

94 / 100

limn-generated spec

Real audit scores. Same product brief.

See how your spec scores

Paste your existing spec and find out exactly what engineers will hit in week three.

Audit your spec — it's free

Pricing

Simple. No surprises.

MonthlyAnnual

Free

£0/month

3 specs to get started. No card required.

✓3 lifetime specs
✓All 6 spec sections
✓[inferred] requirements
✓Web access
–PDF export
–Spec history & regenerate
–Priority generation
Get started for free

Pro

Founding member

£39/month

£19/month

Founding member pricing — available for a limited time

for your first 50 founding members

then £39/month — your rate is locked in forever

For power users and teams who live in specs.

✓Unlimited specs
✓PDF export
✓Full spec history
✓Regenerate & edit
✓Priority generation
✓Team sharing (coming)
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