ZenConverter

ZenConverter is an offline-first file conversion tool for Android. It processes your media and documents directly on your device using native platform APIs, FFmpeg, and on-device neural networks.

No cloud uploads, no ads, no trackers, and no account required. Your files never leave your phone.

Key Features:

Video & Audio (Powered by FFmpeg)
• Convert videos to MP4, MKV, and MOV with customizable codecs, bitrates, resolutions, and frame rates.
• Video merge: concatenate multiple video files into one with aspect-ratio normalization and silent audio track synthesis.
• Visual trimming and multi-segment splitting for long media files.
• Export video overview contact sheets (3x3, 3x4, 4x4, 5x5 grids) with video metadata headers and timestamps.
• Convert videos to animated GIFs with palettegen color optimization.
• Extract audio or convert audio files across MP3, M4A, WAV, FLAC, WMA, and OPUS with bitrate and sample-rate controls.

On-Device AI (Tencent NCNN with Vulkan GPU)
• Image Super-Resolution: Upscale raster images up to 4x using Real-ESRGAN deep-learning models with tiled inference.
• Video Frame Interpolation (Experimental): Double video frame rates (e.g., 30 fps to 60 fps) using RIFE optical flow.

PDF & Document Tools
• Compress PDFs with presets (High Quality, Balanced, Small File) while keeping selectable text and vector layouts intact.
• Merge multiple PDF files, extract selectable text to TXT / Markdown, or apply password encryption and decryption.
• Convert DOCX, PPTX, and XLSX documents to PDF, TXT, or Markdown locally using device system fonts.

Images, Fonts & Subtitles
• Convert between JPG, PNG, WEBP, and ICO. Render PDF pages to images or pack images into a PDF.
• Convert font formats between TTF, OTF, WOFF, and WOFF2.
• Convert subtitle and lyrics files between SRT, VTT, LRC, and ASS with timestamp preservation and encoding fallbacks.
• Metadata Safety: Inspect photo and video metadata (including HEIC/HEIF), and strip EXIF metadata from JPG files without re-encoding.

Modern Android Experience
• Material You dynamic theme integration that matches your system wallpaper.
• System dark theme with an independent pure black toggle for OLED displays.
• In-app language switching supporting English, Simplified Chinese, Traditional Chinese, and French.

Notes:
• ZenConverter runs on arm64-v8a devices.
• Converting large video files or running AI upscaling requires adequate battery, memory, and free storage space.
• ZenConverter is open-source software licensed under the AGPL-3.0.