LeanDeck — Product Case Study

01 · Users & goals

Who it's for and the problem

For design and dev agencies, a proposal takes 6–10 hours, mostly written by hand from scratch. LeanDeck, built for a US client and only for design and dev businesses, drafts it with AI and carries it through to an agreement and an invoice.

I owned the product end to end, including the billing and document journey, and decided where AI should act. I also created the pitch deck and the product positioning.

Who it's for

Agencies: Design and dev agencies that write proposals, agreements and invoices for their clients.
Agency teams: Work on the same documents in shared, multi-user workspaces.

Goals we built against

We didn't set formal metrics, but we built against three clear goals:

Time to beta: A beta with real agencies in eight weeks.
First proposal: A first proposal in about ten minutes.
Output quality: AI output usable as-is, needing only light edits before it's sent.

02 · Key decisions

Deciding where the AI acts

AI returns structured, editable sections

Problem: AI output had to be accurate and consistent every time, and a single block of generated text is hard to check and hard to fix.
Decision: The AI returns a proposal as structured, editable sections, with a section- and sentence-level editor that has AI assistance built in.
Trade-off: More prompt and evaluation work than free-text generation, slower generation, and less freedom for the AI, which has to fit a set section structure.
Worth it because: Agencies can edit, convert and price structured sections. A block of text is something they'd have to rewrite.

AI drafts; invoicing follows fixed rules

Problem: Generative AI could draft every document, but agreements and invoices are financially binding.
Decision: Scoped generative AI to proposal and agreement drafting, and deliberately kept invoicing on fixed rules.
Trade-off: Less automation where it would have been easiest to add, on the position that a plausible-but-wrong invoice is a worse failure than a slower one.
Said no to: AI-generated invoices.

Users can override any AI output

Problem: Financially binding documents need to be reviewable. Users can't be locked into whatever the AI produced.
Decision: Users can accept, edit or override any AI output without losing context. The product says it plainly: “The AI assists; you decide.”
Trade-off: Automation speed traded for the reviewability that financially binding documents require.

03 · Execution

From kickoff to beta in eight weeks

The core flow has four steps: choose a document, answer smart questions, review and refine, deliver. Two problems were harder than the rest: getting accurate, consistent AI output every time, and making the AI's cost and timeline estimates defensible. I wrote and tested the prompts, worked on how the AI finds the right information, and defined the criteria for evaluating AI output. I designed the AI-assisted proposal, agreement and invoicing flows on a scalable Ant Design component library.

Create proposal screen asking who the proposal is for — Smart questions · the AI asks before it drafts

Proposal editor with table of contents and comments — Structured, editable sections with team comments

What was in the beta and what came later

To hit a beta in eight weeks, I kept invoicing rule-based instead of AI-generated (the same line as the decision above), so there was one less place a plausible-but-wrong document could come from. I also moved milestone billing to Phase 2.

What shipped:

AI-generated proposals as structured, editable sections.
A section- and sentence-level editor with AI assistance.
One-click proposal to agreement, with a clause library.
AI cost and timeline estimation.
Invoicing with payment tracking.
Multi-user teams and workspaces.

Built on Django and FastAPI, GPT-5.1 and Next.js. We kicked off on 9 November 2025 and launched the beta in early January 2026 with 6 agencies. Alongside the build I created the pitch deck and the product positioning. Phase 2 (milestone billing) is in progress.

1Choose document
2Answer smart questions
3Review and refine
4Deliver

Flow · choose document → answer smart questions → review and refine → deliver

04 · Outcomes

Beta in eight weeks, now used by 500+ businesses

A proposal or agreement now takes about 5 minutes to create, against 6–10 hours by hand.
Beta launched in 8 weeks: kickoff on 9 November 2025, live in early January 2026.
The beta started with 6 agencies.
500+ design and development businesses use it today.
Live at leandeck.ai, with Phase 2 (milestone billing) in progress.

Customer count as published on leandeck.ai.

After launch: what we changed

Feedback: Agencies asked for more design options, and to paste a client conversation and get their documents from it.
Change: More proposal and agreement designs, and conversation-to-documents: paste the client conversation, and the proposal, agreement and invoice are drafted from it. Invoice amounts still come from the work and prices agreed in the proposal.
Why it mattered: It removed the last manual step: retyping what the client already said.

05 · What I'd do differently

Build the AI test set on day one

I'd build a fixed set of test proposals in week one and score every prompt change against it, instead of judging AI output case by case.