Inspiration
Many English learners know the words in a sentence but still sound translated because the words are combined unnaturally. “Do a decision” is understandable; “make a decision” is what fluent speakers expect.
That small difference is difficult to learn from a dictionary. The learner needs to notice which words belong together, see the expression in context, make the choice, and understand why an alternative sounds unnatural.
We built Colloca for intermediate and advanced learners, IELTS/PTE candidates, students and professionals who want a short, repeatable way to build that instinct. The goal is not to add another vocabulary list. It is to make natural word combinations memorable enough to use in a real sentence.
What it does
Colloca is an offline-first English collocation trainer with exactly 1,000 collocations organised across seven practical topics: Everyday Speaking, Work & Business, Study & Academic, IELTS & PTE Booster, Feelings & Health, Goals & Decisions, and Opinions & Debate.
The learning loop is intentionally small: open an expression, read its examples and common-mistake guidance, hear it with device text-to-speech where available, practise the choice, then save or revisit it. Three modes—Yes / No Challenge, Multiple Choice and Spot Unnatural—provide 3,000 bundled quiz records across the three modes. Daily goals and review state help turn a single correction into a practice habit. A free starter set is available without a Colloca account; the core learning content is bundled locally for offline-first study.
RevenueCat powers one premium entitlement and the current native offering. The paywall presents store-backed Monthly ($5.99), Annual ($19.99 with a three-day introductory trial for eligible customers), and Lifetime ($29.99) options. Learners can dismiss the paywall, continue with free content, and restore an existing purchase from the paywall or Settings.
How we built it
Colloca is built with React Native, Expo SDK 57, Expo Router and TypeScript. Content is bundled and indexed locally; Zustand persists progress, favourites and settings on the device. Platform-specific purchase adapters keep StoreKit and Google Play billing isolated from the web build while the same catalog is mapped through RevenueCat.
The interface uses connected blue and green word blocks as a visual metaphor for collocations. A scholarly owl appears at high-value moments—greeting, practice feedback and celebration—without taking the learner away from the task. The layout adapts to iPhone, iPad and Android safe areas instead of treating a tablet as a stretched phone.
Challenges we ran into
The hard part was making a language explanation feel useful in seconds rather than building a large content catalogue. We had to keep the free path meaningful while protecting premium content, explain a correction without overwhelming the learner, and keep the same interaction understandable across three native billing environments and the web build.
Purchase and restore states were another challenge: a visual paywall is not proof of entitlement. The app now grants PRO only after the native store and RevenueCat confirm the premium entitlement, and it keeps the paywall dismissible when a purchase is interrupted. We also refined notification permission timing so it is requested when a learner chooses to enable daily reminders, not immediately on first launch.
Accomplishments that we're proud of
We shipped a public iOS app with a complete learning loop rather than a static phrase list: context, correction, quiz decision, feedback, save and daily practice. The same content model supports 1,000 collocations, seven topics and 3,000 quiz records while remaining usable offline-first.
We are proud of the connected-word-block design system, the mascot used as focused encouragement, and the responsive iPhone/iPad/Android layouts. We also integrated RevenueCat across native platforms with one entitlement, three transparent price choices and restore-aware UX. The app is publicly available on the US iOS App Store; Android is currently in internal testing.
What we learned
The product is not a dictionary with a paywall. The useful unit is a decision: “Which combination sounds natural here, and why?” Showing the correction immediately, keeping the free path useful, and making the next practice action obvious mattered more than adding another screen.
We also learned to treat the interrupted purchase, the restore path, the first permission prompt and the empty state as part of the product—not edge cases. Our next measurement pass will connect the funnel to evidence: activation, first quiz completion, trial start, paid conversion, retention and restore success. Until those exports exist, we do not claim growth or learning outcomes.
What's next
We will use real App Store and RevenueCat behaviour to improve the learning habit: where learners return, where a quiz stops, which topic starts a session, and which premium option fits their commitment. The next experiment compares the first-session Quick Practice path with a topic-led path and measures activation, quiz completion and trial start with dated baselines.
We also plan learner testing with the intended audience, better explanation variants for common mistakes, and broader Android availability after internal billing and release checks are complete. The priority is measurable usefulness before expanding the catalogue.
Selected category evidence
RevenueCat Design Award
Colloca makes an abstract language problem visible through connected blue and green word blocks: words become useful when they fit together. Highlighted expressions, focused cards and immediate quiz feedback keep the learner on one decision at a time. The scholarly owl appears selectively at greeting, feedback and celebration moments, adding warmth without replacing the content. The video shows the expression-to-quiz transition, the natural/unnatural explanation, mascot interaction, responsive iPad composition and the three-choice paywall.
HAMM Award
Colloca monetises the full learning library while keeping a free starter path available before payment. RevenueCat owns the current offering, product mapping, premium entitlement, purchase callback and restore path. The store-backed catalog is Monthly $5.99, Annual $19.99 with a three-day introductory trial for eligible customers, and Lifetime $29.99. Lifetime is initially selected as the one-time anchor; Annual makes its trial and post-trial price explicit; Monthly remains the low-commitment option. These are pricing hypotheses to measure, not claimed conversion results.
Grand Prize
Colloca launched publicly on iOS during Shipaton and has been iterated through native QA: notification timing, practice-content counts, responsive layouts, paywall disclosure and purchase/restore error handling. We will add a dated App Store Connect and RevenueCat snapshot for installs, active users, trial starts, paid customers, conversion, retention and revenue before the deadline. No growth number is presented until it is exported and attributable.
RevenueCat Peace Prize
Colloca is for learners who need practical communication confidence but may not have continuous connectivity, a tutor or time for a long course. Bundled core lessons, short feedback loops and no required account make independent practice feasible on a commute, in a classroom or with an unreliable connection. The specific intended benefit is replacing literal translations with natural combinations in study, work and exam communication. We will validate that impact with learner testing and repeated-practice evidence rather than infer it from downloads.
Testing notes
No sign-in is required for the core learning flow. Use the public US iOS listing: https://apps.apple.com/us/app/english-collocations-colloca/id6806557814
Suggested walkthrough:
- Open a topic and inspect an expression, examples and common-mistake guidance.
- Try Quick Practice in Yes / No Challenge, then open another quiz mode.
- Save an expression and find it in Saved.
- Open Colloca PRO and compare Monthly, Annual and Lifetime. Eligible App Store customers can test the Annual three-day introductory trial.
- Use Restore Purchases from the paywall or Settings.
Core learning content is bundled locally. Text-to-speech uses device voices where available. Store purchase and restore require the platform store and RevenueCat connection. Android is currently internal testing; the iOS store link is the supported judging path.
Built With
- android
- expo.io
- ios
- react
- revenuecat
- typescript
- zustand
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