Replace the deck with the thing.

The clearest spec is a working version of the feature. Marcus turns a paragraph of intent into a clickable, hosted prototype your team can argue about, your customers can try, and your engineers can use as a brief.

From PRD to prototype in an hour.

Paste the goal, the user, the constraint. Marcus produces a full flow with realistic data, not a wireframe. Stakeholders click instead of squinting at boxes.

Side-by-side variants.

Spin up A and B with one prompt. Send both URLs to ten users. Decide on the version the data preferred — not the one with the loudest opinion in the room.

Real telemetry, no analytics ticket.

Every prototype ships with event tracking on every interaction. You see funnel drop-off, time-on-step, and rage-clicks without booking a meeting with data.

Engineers love what they receive.

The prototype is real code: TypeScript, schema, API contracts, accessibility. It hands off to engineering as a starting point, not a translation problem.

Stakeholder previews, gated.

Give the CEO a read-only link with a passphrase. Give legal a separate link. Revoke any of them with one click. Nobody has to remember which Slack channel the demo lived in.

Decisions log themselves.

Every prompt becomes a line in the changelog. Six weeks later you can see exactly when “Save” became “Send” and why — without trawling Notion.

The PM workflow, rewritten

What Marcus removes from your week.

The “can you mock this up?” email.

You don't send it. You build the mock yourself in fifteen minutes and ship it as a working URL. Your designer reviews the result, not your description of the result.

The two-week “discovery prototype” sprint.

Reduced to an afternoon. Four variants tested with real users on real devices. The cheap experiment becomes cheap enough to actually run.

The “we shipped what?” postmortem.

The shipped version matches the prototype because the prototype is the spec. Translation loss between PRD, design, and code drops close to zero.

The PRD that nobody reads.

You still write one. But it points at a working URL. Engineers, sales, support — they all read the URL because clicking is faster than reading.

“Half my job is translating between people who think in pixels, people who think in tickets, and people who think in dollars. Marcus is the first tool that lets all three look at the same artefact.”
— Group PM, B2B SaaS, in a closed beta interview.

Stop describing the feature. Build it.

Send the working version to the meeting instead of the screenshots.

Build a prototype →