# gmetais/sw-delta

An incremental cache for the web

Repository: https://github.com/gmetais/sw-delta
Canonical: https://ross.abutalabs.com/products/sw-delta
Language: JavaScript
License: GPL-2.0
License Family: copyleft
Last push: 2016-08-27T16:23:49+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 4000, "days_push": 3658, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1098, forks 31 (observed 2026-08-28T04:03:34.773421+00:00)

## What it is
sw-delta is an incremental cache for the web that uses the Service Worker API to download only the delta (diff) between a cached file and its new version. It works client-side via a Service Worker that appends the cached version to requests, and server-side via implementations that compute and serve delta files.

## Use cases
- reduce bandwidth for frequently updated static assets
- speed up websites with continuous delivery and file versioning
- avoid full re-downloads of barely changed JavaScript or CSS files
- implement delta updates in a browser cache
- improve web performance for repeat visitors

## When to choose
- your site deploys new asset versions frequently and users revisit often
- you want a progressive enhancement that falls back to normal caching
- your audience is mostly on Service Worker-supporting browsers over HTTPS

## When to avoid
- you need production-ready, widely supported tooling (the project is experimental and unmaintained since 2016)
- your users rely on browsers without Service Worker support
- you cannot modify server-side code to compute deltas

## Facets
- artifact type: library
- maturity: experimental
- function: caching, http-client, middleware
- domain: web-development, performance, frontend
- platform: browser
- tags: service-worker, delta-updates, webperf, incremental-download, browser-cache, nodejs, web-server

## Member repositories
- gmetais/sw-delta (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:03:34.773421+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 2026-08-30T06:46:19.008709+00:00, confidence not recorded.
  - readme: https://github.com/gmetais/sw-delta (fetched 2026-08-28T04:03:34.773421+00:00, sha 128b08fbee86)
  - registry_npm: https://registry.npmjs.org/sw-delta (fetched 2026-08-29T12:49:28.496713+00:00, sha 77f6dea1c8b9)
- Data as of 2026-08-30T08:39:29.467469+00:00.