# What changed in ipaddr.js

> 9 changes in ipaddr.js 2 from its official release notes, upgrade guides and advisories: 6 breaking, 1 security, 1 new APIs and options. Each one cited. Sources checked 2026-10-26. HTML: https://unstale.sh/npm/ipaddr.js/

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

## ipaddr.js 2

### Breaking changes

- ipaddr.min.js is removed; end users must provide their own minification or bundling. (2.5.0) — [release notes](https://github.com/whitequark/ipaddr.js/blob/dc55282780d8702bac31ef012ca52e4a77fbca1f/Changes.md#250---2026-08-04)
- Strict IPv6 validation now rejects :: with zero compression and hextets longer than four hex digits. (2.5.0) — [release notes](https://github.com/whitequark/ipaddr.js/blob/dc55282780d8702bac31ef012ca52e4a77fbca1f/Changes.md#250---2026-08-04)
- Malformed input now produces a descriptive error. (2.5.0) — [release notes](https://github.com/whitequark/ipaddr.js/blob/dc55282780d8702bac31ef012ca52e4a77fbca1f/Changes.md#250---2026-08-04)
- toString now compresses the leftmost zero run in accordance with RFC 5952, 4.2.3. (2.5.0) — [release notes](https://github.com/whitequark/ipaddr.js/blob/dc55282780d8702bac31ef012ca52e4a77fbca1f/Changes.md#250---2026-08-04)
- toString now compresses a trailing zero run when a zoneIndex is present. (2.5.0) — [release notes](https://github.com/whitequark/ipaddr.js/blob/dc55282780d8702bac31ef012ca52e4a77fbca1f/Changes.md#250---2026-08-04)
- Bower support was removed. (2.4.0) — [release notes](https://github.com/whitequark/ipaddr.js/blob/dc55282780d8702bac31ef012ca52e4a77fbca1f/Changes.md#240---2026-05-03)

### Security

- Rejects non-numeric prefix lengths. (2.5.0) — [release notes](https://github.com/whitequark/ipaddr.js/blob/dc55282780d8702bac31ef012ca52e4a77fbca1f/Changes.md#250---2026-08-04)

### New APIs and options

- Adds a helper to validate IPv4 CIDR in four-part decimal form. (2.3.0) — [release notes](https://github.com/whitequark/ipaddr.js/blob/dc55282780d8702bac31ef012ca52e4a77fbca1f/Changes.md#230---2025-11-27)

### Behavior and default changes

- Added reserved address ranges from RFC9637, RFC9602, RFC8215, and RFC3879. (2.4.0) — [release notes](https://github.com/whitequark/ipaddr.js/blob/dc55282780d8702bac31ef012ca52e4a77fbca1f/Changes.md#240---2026-05-03)