# What changed in proxy

> 8 changes in proxy 3 to 4 from its official release notes, upgrade guides and advisories: 3 breaking, 4 new APIs and options. Each one cited. Sources checked 2026-10-24. HTML: https://unstale.sh/npm/proxy/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## proxy 4

### Breaking changes

- URLs longer than 4096 characters are rejected with HTTP 414 to prevent potential denial of service from excessively long inputs. (4.1.0) — [release notes](https://github.com/TooTallNate/proxy-agents/releases/tag/proxy%404.1.0)
- The minimum supported Node.js version is now 20. (4.0.0) — [release notes](https://github.com/TooTallNate/proxy-agents/releases/tag/proxy%404.0.0)

### New APIs and options

- `proxy-agent-negotiate` has `kerberos` as an optional peer dependency for automatic Negotiate/SPNEGO authentication. (4.1.0) — [release notes](https://github.com/TooTallNate/proxy-agents/releases/tag/proxy%404.1.0)
- Setting `negotiate: true` enables automatic Negotiate/SPNEGO proxy authentication using the `kerberos` package. (4.1.0) — [release notes](https://github.com/TooTallNate/proxy-agents/releases/tag/proxy%404.1.0)
- HttpsProxyAgent and HttpProxyAgent accept an async callback invoked when the proxy responds with 407; it can return headers for retrying the request. (4.1.0) — [release notes](https://github.com/TooTallNate/proxy-agents/releases/tag/proxy%404.1.0)
- A new package provides shared Negotiate/SPNEGO authentication logic for proxy agents. (4.1.0) — [release notes](https://github.com/TooTallNate/proxy-agents/releases/tag/proxy%404.1.0)

### Behavior and default changes

- Package exports no longer impose an unnecessary imports restriction. (4.0.0) — [release notes](https://github.com/TooTallNate/proxy-agents/releases/tag/proxy%404.0.0)

## proxy 3

### Breaking changes

- All packages now use ESM and compile to ESM output instead of CommonJS, affecting how developers consume the packages. (3.0.0) — [release notes](https://github.com/TooTallNate/proxy-agents/releases/tag/proxy%403.0.0)