(registered 2026-07-21, last updated 2026-07-21)

Media type name: application

Media subtype name: vnd.portableweb+zip

Required parameters: N/A

Optional parameters: N/A

Encoding considerations: binary

Security considerations: PortableWeb (Portable Web Content Format) packages may contain active content, including HTML, JavaScript, and WebAssembly. Implementations must treat packages as untrusted input. Viewers that execute active content must isolate it from the host environment and must not grant access to files, credentials, storage, networking, device APIs, navigation, downloads, or other privileged capabilities unless permitted by both the viewer policy and, where applicable, the package manifest. Manifest declarations are capability requests, not authorization.

PortableWeb may contain sensitive information, but the media type provides no confidentiality, integrity, authentication, authorization, or replay protection. When required, these protections must be provided externally through mechanisms such as TLS, trusted distribution, operating-system protections, checksums, digital signatures, or application-level validation.

PortableWeb uses a compressed ZIP container, a JSON manifest, and may contain HTML, CSS, JavaScript, WebAssembly, and other media. The security considerations of those formats apply. Implementations must validate the manifest and resource references, enforce package boundaries, avoid unsafe content sniffing, and protect against decompression bombs, resource exhaustion, path traversal, absolute or ambiguous paths, duplicate entries, symbolic links, and filename-normalization conflicts. Extracted content must remain within an application-controlled location.

External resources are not required to identify the media type or process the ZIP container and manifest. Package content may contain external links or network requests. Viewers must distinguish external resources from packaged resources and control access according to the viewer or user policy.

Interoperability considerations: PortableWeb packages are ZIP-based containers containing a UTF-8 JSON manifest that identifies the format version, entry resource, packaged resources, and requested capabilities. Interoperability depends on consistent interpretation of the manifest, package-relative resource paths, and package boundaries.

Rendering may vary according to the web engine, supported media codecs and fonts, optional platform features, and viewer security policy. Unknown optional manifest fields may be ignored when they can be safely processed in that manner.

There are no prior published payload versions that are incompatible with the version current at publication time.

Published specification: https://portableweb.org/spec/

Applications which use this media: Applications that create, package, inspect, validate, store, distribute, archive, or render PortableWeb packages. These may include PortableWeb viewers, authoring and packaging tools, validation tools, file managers, document-management systems, web servers, and archival systems.

The format is used for interactive presentations, educational explainers, games, interactive reports and supplements, personal tools, and other packaged web-based experiences, including AI-generated interactive artifacts distributed as files rather than deployed to a web server.

Fragment identifier considerations: Fragment identifier semantics are not defined by this media type registration for the PortableWeb package container as a whole. If a future version of the PortableWeb specification defines PortableWeb-specific fragment identifier syntax for addressing packaged resources or internal navigation targets, this registration should be updated to describe those semantics.

Restrictions on usage: There are no restrictions on usage imposed by this media type registration.

Additional information:

1. Deprecated alias names for this type: N/A
2. Magic number(s): 50 4B 03 04 (PK\003\004) (.pweb files are ZIP-based containers and therefore use the ZIP container signatures)
3. File extension(s): .pweb
4. Macintosh file type code: N/A
5. Object Identifiers: N/A

General Comments: PortableWeb (Portable Web Content Format) packages provide a portable, self-contained packaging format for interactive web content that can be saved, shared, archived, and opened by a compatible viewer. The preferred file extension is “.pweb”.

Project website: https://portableweb.org
Github: https://github.com/portableweb

Person to contact for further information:

1. Name: Omprakash Selvaraj
2. Email: maintainer&portableweb.org

Intended usage: COMMON

Author/Change controller: Omprakash Selvaraj maintainer&portableweb.org