Prompt Bnk

A subscription library of 150 prompts, found by category.

The brief

A UK startup wanted people with little experience of writing prompts to get better, more reliable answers from language models. The brief was a subscription library where they could find a good prompt and use it straight away.

The Prompt Bnk library: the monthly prompt count, a search box, fifteen categories to filter by down the side, and prompt cards tagged by category — The library, by categoryScreenshot, demo data, name shown as Prompt Bnk2025 to 2026

Who it is for

Businesses, startups and professionals who use AI tools at work, many without much practice at writing prompts.

The same prompt opened on a phone, with buttons to copy it, share it or open it in a chat assistant — A prompt, ready to copyScreenshot, demo data2025 to 2026

The prompt on a phone, with its measurements in the margins: type sizes, padding, a 44 by 44 pixel close button and colour swatches — A prompt, ready to copyScreenshot, demo data2025 to 2026

Choose Your Plan on a phone: a monthly and yearly switch above the Free and Starter plans — Choosing a planScreenshot, demo data2025 to 2026

Choose Your Plan on a phone, with its measurements in the margins: type sizes, padding, radii and colour swatches — Choosing a planScreenshot, demo data2025 to 2026

Decisions

Discovery starts from the category, the kind of work in front of you, across 15 of them.

Every prompt was rated on clarity, consistency, relevance, efficiency and effectiveness before it went in.

Access is gated by subscription, and usage metrics track how each prompt is used and how well it works.

I built it first as a single monolith, with no tracking for admins. I then refactored it into a modular monolith, with payments and analytics modules, and added admin tracking.

Choose Your Plan: Free, Starter and Pro side by side, with a monthly and yearly switch — The plansScreenshot, demo data2025 to 2026

Choose Your Plan with measurements laid over it: type sizes, padding, button sizes, radii and colour swatches — The plansScreenshot, demo data2025 to 2026

Monthly Quota Reached: all four prompts used, the date the quota resets, and an Upgrade Plan button — The monthly quota, reachedScreenshot, demo data2025 to 2026

Monthly Quota Reached with measurements laid over it: type sizes, padding, the button size and colour swatches — The monthly quota, reachedScreenshot, demo data2025 to 2026

The admin analytics dashboard: totals for users, active subscriptions, revenue and prompts accessed, above a subscription breakdown chart — The analytics dashboardScreenshot, demo data2025 to 2026

The analytics dashboard with measurements laid over it: type sizes, padding, tile sizes and colour swatches — The analytics dashboardScreenshot, demo data2025 to 2026

Flows

BrowseStart from one of 15 categories.
OpenOpen a rated prompt.
SubscribeA subscription opens the library.
Copy and useCopy the prompt into the AI tool you already use.

Find, copy, useDiagram, built in code2025 to 2026

Screens

The admin settings moving through categories, user management, subscriptions and analytics — The admin toolsScreen recording, demo data2025 to 2026

User management: a table of demo users with their role, status and last sign-in — Managing usersScreenshot, demo data2025 to 2026

Subscription and billing: the current plan, a usage meter showing 5 of 16 prompts used, and billing details — Subscription and billingScreenshot, demo data2025 to 2026

Subscription and billing with measurements laid over it: type sizes, padding, the meter height and colour swatches — Subscription and billingScreenshot, demo data2025 to 2026

The sign-in card with measurements laid over it: type sizes, padding, field and button sizes and colour swatches — Signing inScreenshot, demo data2025 to 2026

What testing found

In testing, people completed 19 of 20 tasks, with a median of 32 seconds to the first useful prompt.

Test tasks completed: 19 of 20
Perceived usability, out of 100: 84.5
Subscribers in the launch period: 50+

Tokens

Read from the code I wrote.

purple-600: #9333EA, oklch(0.558 0.252 302.3)
purple-700: #7E22CE, oklch(0.496 0.237 301.9)
gray-900: #111827, oklch(0.21 0.032 264.7)
gray-700: #374151, oklch(0.373 0.031 259.7)
gray-600: #4B5563, oklch(0.446 0.026 256.8)
gray-200: #E5E7EB, oklch(0.928 0.006 264.5)
gray-50: #F9FAFB, oklch(0.985 0.002 247.8)
white: #FFFFFF, oklch(1 0 0)
1: 4px (0.25rem)
2: 8px (0.5rem)
3: 12px (0.75rem)
4: 16px (1rem)
6: 24px (1.5rem)
8: 32px (2rem)
rounded: 4px (0.25rem)
rounded-md: 6px (0.375rem)
rounded-lg: 8px (0.5rem)
rounded-xl: 12px (0.75rem)
rounded-2xl: 16px (1rem)
font: ui-sans-serif, system-ui, sans-serif

ShowcaseSpecs