Whitespace.
See who already built your idea — and the space they left open.

CLUSTER MOBILE-DOCUMENT-OTHER · 18 ENTRIES · EARLIEST ENTRY 2016-10-24

Mobile document readers and annotators

This cluster comprises mobile document viewers and editors, predominantly focused on PDF reading, annotation, editing, and file management. Entries appear irregularly from 2011 to mid-2026, with the largest single month being April 2026 (3 entries). The traction leaders are MJ PDF, Readwide, and PDF Viewer by Nutrient, each with 0 stars, showing minimal observable traction.

Entry timeline

ENTRY TIMELINE

DEC 2010: 1AUG 2011: 1OCT 2016: 2JAN 2019: 1MAR 2019: 1APR 2021: 1AUG 2021: 1JUN 2023: 1APR 2024: 1APR 2026: 2MAY 2026: 1JUN 2026: 2JUL 2026: 1AUG 2026: 1SEP 2026: 1
DEC 2010SEP 2026

Each bar is the month a member carries, which is a creation date where the source published one and a crawl date otherwise. Nothing in the index was found before 11 August 2026, and coverage broadened sharply on 14–15 August, so a bar from then on reports how much we found that month, not how much was built; an earlier bar reports how far back a member's own source dated it — not how long we have been watching.

Members by activity

Activity signals, not revenue.

Build origin · 3 hand-coded · 15 unlabelled

Operator · 2 hobby · 6 commercial · 8 open source · 2 unlabelled

Two labels per entry, never collapsed into one: how it was built, and who stands behind it. Counted over the 18 listed below. Unlabelled means nothing has decided yet — not that the answer is small.

  1. 01Readwide0★22 daysliveopen sourceLocal-first Android reader and file browser supporting many document formats including PDF, EPUB, Markdown, with file management.
  2. 02PDF Viewer by Nutrient0★1 molivecommercialPDF viewer and annotator for mobile, supporting cloud storage, search, and markup tools.
  3. 03mirevaBook0★29 days—hobbyMobile PDF reader that manages a local library, tracks reading progress, and resumes documents from the last page.
  4. 04MJ PDF0★1 moliveopen sourceAndroid PDF viewer and library manager with annotation, form filling, and ebook-like reading modes.
  5. 05SideBooks0★1 moliveMobile PDF viewer that lets users read documents and comics with realistic page-turn animations and organize them in virtual bookshelves.
  6. 06PDF Reader : Document Reader0★3 molivecommercialMobile PDF reader that scans, lists, opens, annotates, signs, and manages PDF and office documents locally on the phone.
  7. 07PDF Reader & Editor - Ora Docs0★1 molivecommercialMobile document reader that opens Office files, PDFs, eBooks, code files, and media, with basic editing and file management.
  8. 08Okular0★3 moliveopen sourceUniversal document viewer that displays and annotates PDFs, images, ebooks, and other formats across multiple platforms.
  9. 09Okular Mobile0★1 moliveopen sourceMobile document viewer that displays and annotates PDFs and other formats on mobile devices.
  10. 10MuPDF mini0★17 daysliveopen sourceAndroid document viewer that displays PDF, XPS, CBZ, EPUB, and FB2 files with zoom, links, and table of contents.
  11. 11marginalia0★2 molivehand-codedhobbyMobile-first reading annotation PWA that lets users log books, capture screenshots, and write notes per page, syncing via Supabase.
  12. 12GoodReader Pro PDF Editor0★13 dayslivehand-codedcommercialMobile document reader and file manager that lets users view, annotate, highlight, edit, and organize PDF documents and other files.
  13. 13PDF Reader – PDFelement0★2 yrabandonedlivecommercialPDF reader for mobile that provides reading, annotation, form signing, and cloud services, with a liquid mode for comfortable viewing.
  14. 14PDF Pro - Reader Editor Forms0★1 molivecommercialPDF reader and editor for mobile that reads, annotates, highlights, and draws on PDFs, with form filling, signature support, and full-text search.
  15. 15Mark PDF Editor : PDF Smart0★6 mostaleliveMobile app for viewing, editing, annotating, and organizing PDF documents with highlighting and note-taking features.
  16. 16OpenPaperView0★9 mostalelivehand-codedopen sourceMobile companion app that browses, searches, downloads, and displays documents from Paperwork, usable offline.
  17. 17Print0★2 yrabandonedliveopen sourceMobile utility that prints or exports shared documents and text to PDF, rendering markdown formatting, tables, and clickable links.
  18. 18Orion Viewer - Pdf & Djvu0★10 daysliveopen sourceMobile viewer app for reading PDF, DjVu, XPS, TIFF, and comic book files, with bookmarks, outline navigation, and dictionary lookup.

Ranked by traction, highest first, and paged 20 at a time — this is a window on the cluster, never the whole of it. Ties are broken by a stable id so a product cannot appear on two pages or fall between them. Browse every cluster.