Android Developer – Document Reading & Annotation App (Java/Kotlin)

DDT Software & E-Commerce Pvt. Ltd. is building a next-generation active reading and document annotation app for Android tablets and phones

. Users will be able to open PDFs and documents, highlight, annotate with a stylus, pull excerpts into a free-form workspace, link ideas together, and organise research visually. We need an Android developer with strong skills in custom rendering, touch/stylus input and performance optimisation to help build it from the ground up.

Key Responsibilities

  • Build the core

    PDF/document viewer with smooth scrolling, zooming and page rendering

  • Develop annotation tools such as highlights, freehand ink, shapes, text notes, comments and bookmarks

  • Implement stylus and multi-touch input

    , including pressure sensitivity, palm rejection, pinch-to-zoom and gesture handling

  • Build a free-form canvas workspace where users drag excerpts out of documents, group them, connect them, and link back to the source page

  • Support multi-document views with side-by-side and split-screen layouts

  • Add full-text search across documents and annotations, with OCR for scanned PDFs

  • Export annotated documents as PDF with annotations flattened or kept editable

  • Design local storage and sync logic for documents, annotations and workspaces, with offline-first behaviour

  • Optimise for large documents

    (500+ pages) through bitmap tiling, caching, memory management and background rendering

  • Build tablet-first, adaptive UI that also works on phones and foldables

  • Manage Play Store releases, crash monitoring and performance profiling

Required Skills & Experience

  • 3–4 years of native Android development in

    Kotlin and Java

  • Strong experience with custom Views / Canvas drawing or

    Jetpack Compose Canvas

  • Hands-on work with

    PDF rendering libraries

    : Android PdfRenderer, PDFium, MuPDF, or commercial SDKs such as PSPDFKit/Nutrient or Apryse

  • Solid understanding of

    MotionEvent, gesture detection and multi-touch handling

  • Experience with bitmap management, memory optimisation and avoiding OOM issues in graphics-heavy apps

  • Strong

    Kotlin Coroutines/Flow and background processing skills

  • MVVM / Clean Architecture with Jetpack (ViewModel, Room, Navigation, WorkManager)

  • Experience with the

    Storage Access Framework and scoped storage for opening and saving user files

  • Profiling skills with Android Studio Profiler, systrace/Perfetto and LeakCanary

  • At least one shipped app involving a PDF viewer, note-taking, drawing/whiteboard, e-reader, or similar graphics-heavy work (Play Store link required)

Good to Have (Added Advantage)

  • Stylus/ink SDK experience, such as Android Ink API, Samsung S Pen SDK or low-latency ink rendering

  • OCR and text extraction

    : Google ML Kit or Tesseract

  • Knowledge of the

    PDF specification and annotation standards (XFDF, PDF annotation objects)

  • Undo/redo stack and command-pattern implementation

  • Cloud sync and conflict resolution with Firebase or a custom REST backend

  • React Native experience for cross-platform modules

  • Node.js for building or integrating backend APIs

  • OpenGL ES / Vulkan or hardware-accelerated rendering

  • Importing DOCX, PPT, EPUB or web articles into a reading view

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