# polyfillpolyfill/polyfill-service

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7,144 stars · 671 forks · JavaScript · MIT

## Links

- GitHub: https://github.com/polyfillpolyfill/polyfill-service
- Homepage: https://polyfill.io/
- awesome-repositories: https://awesome-repositories.com/repository/polyfillpolyfill-polyfill-service.md

## Topics

`origami` `polyfill` `polyfill-service` `service` `systemcode-origami-polyfill-service`

## Description

Polyfill Service is a server that automatically selects and delivers JavaScript polyfills based on the requesting browser's capabilities. It reads the User-Agent header of each request to determine which polyfills are needed, ensuring that only the code required for that specific browser is served.

The service assembles polyfill bundles on the server at request time, generating custom JavaScript payloads per client. It uses runtime feature detection to decide which polyfills to include, avoiding unnecessary code for modern browsers, and sends these bundles as streaming responses for progressive loading. A versioned polyfill repository allows precise matching of polyfill versions to browser requirements.

The project maintains a collection of polyfills that can be conditionally loaded based on browser support, reducing payload size for modern browsers while ensuring compatibility for older ones.

## Tags

### Web Development

- [Browser Polyfill Servers](https://awesome-repositories.com/f/web-development/browser-polyfill-servers.md) — Is a server that automatically selects and serves polyfills based on browser capabilities.
- [User-Agent-Based Polyfill Selection](https://awesome-repositories.com/f/web-development/browser-integration-utilities/browser-apis/user-agent-generators/user-agent-validators/user-agent-based-polyfill-selection.md) — Reads the User-Agent header to select and serve only the polyfills needed for that browser.
- [Runtime Bundling](https://awesome-repositories.com/f/web-development/feature-detection-polyfills/runtime-bundling.md) — Ships a server that bundles polyfills at runtime based on feature detection results.
- [Browser-Specific Delivery](https://awesome-repositories.com/f/web-development/legacy-browser-polyfills/browser-specific-delivery.md) — Serves browser-specific polyfills by reading the User-Agent header of each request. ([source](https://cdn.jsdelivr.net/gh/polyfillpolyfill/polyfill-service@main/README.md))
- [User-Agent-Tailored Delivery](https://awesome-repositories.com/f/web-development/legacy-browser-polyfills/user-agent-tailored-delivery.md) — Automatically serves polyfills tailored to the requesting browser's User-Agent.
- [Conditional Loading](https://awesome-repositories.com/f/web-development/native-lazy-loading-polyfills/conditional-loading.md) — Provides a server that conditionally loads polyfills based on browser feature detection.
- [Server-Side Polyfill Assembly](https://awesome-repositories.com/f/web-development/server-side-polyfill-assembly.md) — Provides a server that assembles custom polyfill bundles per request at runtime.
- [UA-Based Polyfill Delivery Services](https://awesome-repositories.com/f/web-development/ua-based-polyfill-delivery-services.md) — Delivers targeted JavaScript polyfills by parsing the User-Agent header of each request.
- [Response Streaming](https://awesome-repositories.com/f/web-development/backend-development/request-response-handling/http-response-handling/response-streaming.md) — Delivers polyfill bundles as streaming HTTP responses for progressive loading.
- [Versioned Polyfill Repositories](https://awesome-repositories.com/f/web-development/versioned-polyfill-repositories.md) — Maintains a versioned repository of polyfills for precise browser-specific delivery.