RetroFITS
A high-performance FITS image viewer for the terminal. Renders images directly in modern terminal emulators via Kitty, iTerm2, Sixel, or halfblocks graphics protocols, with interactive zoom/pan, colormaps, stretch functions, and a full FITS header viewer.
Kind
GitHub repo
Author
Jae-Joon Lee (leejjoon)
Added
August 26, 2026
RetroFITS uses memory-mapping and a zero-copy architecture to view large astronomical FITS files directly in the terminal — no separate GUI viewer needed, including over SSH. Supports multi-extension files, vim-style navigation, cycling through color maps and stretch functions (Linear, Log, Asinh), cut modes (MinMax, ZScale, Custom), and a crosshair pixel readout showing FITS coordinates and value under the cursor.
Written in Rust. Static, zero-dependency binaries available on the GitHub Releases page.