PDF, Word (.docx), PowerPoint (.pptx), Excel (.xlsx), CSV and TSV, Apache Parquet (the first 10,000 rows), Visio (.vsdx), draw.io (.drawio, and SVG and PNG exports with the diagram), AutoCAD DXF, Jw_cad (.jww), SXF (.p21, .p2z, .sfc), CGM (.cgm), HP-GL/2 plot files (.plt), Gerber and Excellon PCB files (one by one, or a board's files in a .zip), Illustrator (.ai), Photoshop (.psd, .psb), Windows metafiles (.emf, .wmf), images (PNG, JPEG, GIF, WebP, AVIF, BMP, ICO, SVG: shown as they are, with their metadata), audio files (MP3, M4A, FLAC, Ogg, WAV, AIFF: their cover art, tags and lyrics on a card that plays), HTML and web archives (.html, .mhtml) and Markdown (.md) and EPUB (.epub), laid out in reader mode, music (MML, MIDI and MusicXML: .mml, .mid, .kar, .musicxml, .mxl), engraved as scores that play, font files (.ttf, .otf, .ttc, .woff: their characters, glyphs and OpenType features), or BDF. The file is converted to BDF and drawn inside your browser, by the Go converters built as WebAssembly: it is not uploaded anywhere.
Or open a sample:
Password-protected files open with their password. A PDF shows its pages as they are converted, the ones in view first. Music plays with ▶ (or the space bar), and a click on a system plays from there. Use Display to switch between Score, Piano roll and Guitar TAB; choose a TAB part and an estimated fingering. Speed (%) adjusts playback while preserving tempo ratios, and Metronome plays the beat. An audio file plays the same way, with a slider for its position; lyrics that carry their times are marked line by line as they are sung, and a click on a line plays from it. Office documents are laid out with the free fonts published with this page (fetched when a document uses them), which stand in for the fonts the document names.
The thumbnails and the text for a search index that a server makes of a document have pages of their own: thumbnails, search text. What BDF is and how it works: documentation.