# dropbox/lepton

Lepton is a tool and file format for losslessly compressing JPEGs by an average of 22%.

Repository: https://github.com/dropbox/lepton
Canonical: https://ross.abutalabs.com/products/dropbox-lepton
Homepage: https://blogs.dropbox.com/tech/2016/07/lepton-image-compression-saving-22-losslessly-from-images-at-15mbs/
Language: C++
License: Apache-2.0
License Family: permissive
Topics: jpeg, lossless-compression-algorithm, decompression, compression-algorithm, compression
Archived: true
Last push: 2024-03-04T16:56:20+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 3703, "days_push": 912, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 4996, forks 347 (observed 2026-08-28T04:09:04.420385+00:00)

## What it is
Lepton is a command-line tool and file format from Dropbox that losslessly compresses JPEG files by an average of 22% while allowing exact reconstruction. It is written in C++ and supports pipes, batch processing, and configurable memory limits.

## Use cases
- compress jpeg files losslessly
- archive large photo collections to save disk space
- reduce image bandwidth when serving jpegs
- roundtrip compress and decompress jpg files
- compress jpegs via unix pipes in a pipeline

## When to choose
- you need bit-exact JPEG compression savings for archival storage
- you want to serve original JPEGs with ~22% bandwidth reduction
- you need a proven C++ tool with pipe support for image pipelines

## When to avoid
- starting a new project - the repo is deprecated and archived with unfixed security issues
- you can adopt modern formats like WebP or JPEG XL instead
- you need active maintenance and timely vulnerability fixes
- consider Microsoft's Rust implementation of Lepton instead

## Facets
- artifact type: cli-tool
- maturity: abandoned
- function: compression, image-processing
- domain: files, image-processing, developer-tools
- platform: windows, cli, cross-platform
- tags: jpeg, lossless-compression, cpp, deprecated, archived, linux, macos

## Member repositories
- dropbox/lepton (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:04.420385+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T18:17:37.162517+00:00, confidence not recorded.
  - readme: https://github.com/dropbox/lepton (fetched 2026-08-28T04:09:04.420385+00:00, sha 89334bee6478)
  - homepage: https://blogs.dropbox.com/tech/2016/07/lepton-image-compression-saving-22-losslessly-from-images-at-15mbs/ (fetched 2026-08-29T08:58:36.796683+00:00, sha 3c57aac981ee)
- Data as of 2026-08-30T08:39:29.467469+00:00.