# polyfillpolyfill/polyfill-service

Automatic polyfill service.

Repository: https://github.com/polyfillpolyfill/polyfill-service
Canonical: https://ross.abutalabs.com/products/polyfill-service
Homepage: https://polyfill.io/
Language: JavaScript
License: MIT
License Family: permissive
Topics: origami, service, systemcode-origami-polyfill-service, polyfill-service, polyfill
Last push: 2024-07-09T15:09:53+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": 4451, "days_push": 785, "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 7138, forks 675 (observed 2026-08-28T04:09:56.162837+00:00)

## What it is
Polyfill.io is a web service that automatically serves JavaScript polyfills tailored to each browser. It inspects the User-Agent header of incoming requests and returns only the polyfills the requesting browser needs, reducing unnecessary payload.

## Use cases
- serve browser-specific polyfills automatically
- support older browsers without bundling every polyfill
- self-host a polyfill CDN for my web app
- reduce JavaScript payload by only loading needed polyfills
- make modern JavaScript features work in legacy browsers
- add a polyfill script tag that adapts per browser

## When to choose
- you need to support a wide range of browsers including legacy ones
- you want a drop-in script tag instead of manual polyfill management
- you want to self-host the service to control availability and supply-chain risk

## When to avoid
- you target only evergreen modern browsers and need no polyfills
- you prefer build-time polyfill injection via tools like core-js and Babel
- you require a fully offline or air-gapped dependency
- you are concerned about third-party script supply-chain risk from hosted instances

## Facets
- artifact type: service
- maturity: maintenance
- function: http-server, web-framework, developer-tools
- domain: web-development, frontend, developer-tools, apis
- platform: self-hosted, cloud
- tags: polyfills, browser-compatibility, user-agent-sniffing, cdn, javascript-polyfills, cross-browser, nodejs, web-server

## Member repositories
- polyfillpolyfill/polyfill-service (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:56.162837+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 2026-08-29T17:40:02.412501+00:00, confidence not recorded.
  - readme: https://github.com/polyfillpolyfill/polyfill-service (fetched 2026-08-28T04:09:56.162837+00:00, sha 03ffecc8bcfb)
- Data as of 2026-08-30T08:39:29.467469+00:00.