ByteNest Book a free call

Case study 06Communication for childrenCroatiaOngoing

AAC communication app

Picture cards that speak correct Croatian, for autistic children.

The communication book in Croatian, open on the Food (Hrana) page: picture cards for bread, cheese, egg, soup, biscuit and chocolate, colour-coded folder tabs down the side, and a sentence strip at the bottom reading Hoću Keks (I want a biscuit) with a speak button
The quick sentences screen (Brze rečenice) in Croatian with three saved sentences, I am hungry, Give me juice and I am going to sleep, each shown as its picture cards; the middle one is highlighted green while it is being spoken
The communication book mid-sentence, and a saved sentence being spoken.

A Croatian-first app for autistic children. The cards speak in a preset voice that follows Croatian grammar, or in the parents' own voice with the family's own photos. The child learns with flashcards, taps saved sentences and builds new ones in a communication book. Built with a speech and language therapist.

Role
Design and build
Built with
A speech and language therapist
Status
Ongoing
Process
Seven feedback rounds so far

The brief

Cards made by the people who know the child.

AAC means augmentative and alternative communication: picture cards a child taps to be heard. The app ships with hundreds of cards and a preset voice that speaks each word in the form Croatian grammar asks for; that voice is being re-recorded with ElevenLabs or an open-source speech engine. Parents who prefer it record their own voice and use their own photos instead. We design and build it with a speech and language therapist, local-first, with no third-party SDKs.

System map

How it fits together

AAC communication app architectureThe app ships with a voice pack: hundreds of picture cards, each word recorded in every form Croatian grammar needs, and a grammar resolver picks the right form before a sentence is spoken in child mode. Parents can instead add their own photos and record their own voice in a PIN-protected parent mode. Everything is stored in a local SQLite database on the phone, with zip backup and restore.01 PEOPLE02 PARENT03 DEVICE04 CHILD05 PEOPLEVoice packhundreds of cards,every form recordedGrammar resolverpicks the formthe sentence needsChild modeflashcards, sentences,communication bookThe childtaps the cards,hears the sentenceParentsown photos,own voiceParent modePIN-protectedfolders, cardsLocal databasedrift / SQLiteno third-party SDKsBackup, restoreone zip fileschema migrations123 AAC communication app architectureThe app ships with a voice pack: hundreds of picture cards, each word recorded in every form Croatian grammar needs, and a grammar resolver picks the right form before a sentence is spoken in child mode. Parents can instead add their own photos and record their own voice in a PIN-protected parent mode. Everything is stored in a local SQLite database on the phone, with zip backup and restore.01 PEOPLE02 PARENT03 DEVICE04 CHILD05 PEOPLEVoice packhundreds of cards,every form recordedGrammar resolverpicks the formthe sentence needsChild modeflashcards, sentences,communication bookThe childtaps the cards,hears the sentenceParentsown photos,own voiceParent modePIN-protectedfolders, cardsLocal databasedrift / SQLiteno third-party SDKsBackup, restoreone zip fileschema migrations123
System map of AAC communication app. The four stages next to it describe each layer in words.
  1. 1
    A preset voice that speaks correct CroatianHundreds of ready cards; each word is spoken in the form the sentence needs
  2. 2
    Or the family's own voice and photosBehind a PIN, parents record themselves and add their own pictures
  3. 3
    Everything stays on the phonedrift over SQLite, no third-party SDKs, one zip backs it all up
  4. 4
    Three hard partsSmall app, high stakes

Three hard parts

Small app, high stakes

  1. Croatian grammar, handled

    A spoken sentence has to be correct Croatian, and words change with their role in it: jabuka (apple) becomes jabuku after Hoću (I want). A grammar resolver picks the right form for every card in the sentence, and the voice pack carries a recording of each form, so the app never speaks a wrong ending.

  2. A backup parents can trust

    Parents' recordings must survive a lost or new phone. One zip holds a live database snapshot plus every photo and recording, and restore validates it first.

  3. A screen that never moves

    Cards must stay where the child learned them. The grid never re-flows, a PIN gate keeps settings out of reach, and automated tests check WCAG contrast and font coverage.

On screen

For the child, and for the parents

The communication book in Croatian, open on the Basics (Osnovno) page: cards for yes, no, more, done, help and I want on a notebook-style page, colour-coded folder tabs down the side, and an empty sentence strip at the bottom
The book: a page per folder, tabs to flip, a strip to build the sentence in.
The Feelings folder in Croatian: six picture cards for happy, sad, angry, scared, tired and ill
Learning cards: the Feelings folder.
The new card form in Croatian: add a picture, type the word, record a voice or add a video, with switches to hide a card or mark it unavailable
A parent making a card: their photo, the word, their own voice.
Parent settings in Croatian: card packs of 330 and 560 cards, backup and restore of all folders, cards and recordings in one file, and the child grid size
Parent settings: card packs, backup, grid size.

Stack

  • Flutter
  • Riverpod
  • drift
  • SQLite
  • go_router
  • Accessibility tests

Our role: design and build, with a speech and language therapist.

Book a free call Back to all work