The Block Protocol: Making Web Blocks Universal and Reusable

Imagine using a Kanban board block in your blog editor, or a fancy calendar from a note-taking app right in your CMS. That’s the dream behind the Block Protocol. This open, free standard aims to make blocks interchangeable across any web editor, so developers only build a block once and users can access thousands of block types without being locked into a single platform. Below we answer the most common questions about this initiative.

What is the Block Protocol and why was it created?

The Block Protocol is an open, non-proprietary specification that defines how an embedding application (like a blog editor, note-taking app, or CMS) can embed a block (like a paragraph, image, video, Kanban board, or order form). It was created because nearly every web editor has its own proprietary block system, forcing developers to re-implement every block type from scratch. Users suffer too: they can only use blocks that their specific editor supports. The Block Protocol aims to make blocks universally compatible, so a block built once works everywhere. It’s still in early draft, with sample blocks and a simple editor already being developed.

How does the Block Protocol solve the problem of non-standard blocks?

Currently, every app that wants to offer blocks must code each one from scratch. Want a calendar block? Build it yourself. As a result, users are limited to whatever blocks the app developer had time to implement. The Block Protocol standardizes the interface between a block and its host application. If an app follows the protocol, it can embed any block that also follows the protocol. This means a developer can create a block once—say, a fancy image gallery—and any compliant editor (WordPress, Notion, Medium, or a new note-taking app) can use it immediately. No more re-implementing the same features; the protocol handles communication and rendering. This dramatically expands the variety of blocks available to end users without extra work for app developers.

Who benefits from the Block Protocol—app developers or end users?

Both groups benefit greatly. App developers only need to write the embedding code once to support the protocol, instantly gaining access to a growing library of blocks created by others. They no longer have to prioritize which block types to build; their users can choose from any compliant block. End users win because they are no longer restricted to the blocks built into their current editor. If they see a cool Kanban board or interactive order form in another platform, they can use it in their favorite app—as long as both support the Block Protocol. This freedom encourages innovation and gives users the best tools for their content, regardless of which editor they prefer. The protocol is 100% free and open, so there’s no cost barrier for anyone.

What kinds of blocks can be created with the Block Protocol?

Virtually anything that makes sense in a document or on the web can be a block under this protocol. That includes basic elements like paragraphs, lists, tables, diagrams, and rich media like videos and images. It also covers interactive widgets such as Kanban boards, calendars, order forms, and maps. Because the protocol supports structured or typed data, blocks can be smart—for example, a contact form block that emits JSON data for the hosting app to process. The philosophy is simple: if it can be used within a content editor, it should be able to conform to the Block Protocol. The goal is to create a massive open source library of blocks covering every need, from simple formatting to complex business tools.

Is the Block Protocol free and open source? How can I get involved?

Yes, the Block Protocol is completely free, non-proprietary, and open. The specification is released as an early draft, and all sample code demonstrating how to use the protocol is open source. The creators are fostering an open source community to build a huge library of blocks. Anyone can contribute by developing new blocks, improving the protocol itself, or building compliant editors. You can get involved by visiting the project’s website, joining the community discussions, and trying out the early draft. Whether you’re a seasoned developer or a curious blogger, your feedback and contributions are welcome. The vision is a web where blocks are as interchangeable as hyperlinks—and that starts with an open, collaborative community.

How does the Block Protocol compare to existing block systems in WordPress or Notion?

WordPress, Notion, and Medium all have their own block editors, but each system is proprietary and incompatible with others. For instance, a Kanban block built for WordPress doesn’t work in Notion, and vice versa. The Block Protocol doesn’t replace these systems; instead, it provides a universal layer on top. Any editor that adopts the protocol can embed blocks from any other compliant system. This is similar to how HTML is a standard that all browsers support—the protocol standardizes the interface between blocks and their hosts. Existing editors can add support for the Block Protocol alongside their native blocks, giving users the best of both worlds. The key difference is interoperability: with the protocol, a block created for one app instantly works in hundreds of others, ending the fragmentation that limits users today.

What are the technical requirements for an app to support the Block Protocol?

An embedding application (like a blog editor or CMS) needs to implement the Block Protocol’s interface for hosting blocks. This typically involves providing a container element, handling messaging between the block and the host (e.g., resize events, data updates), and allowing the block to be saved and loaded. The block itself must also conform to the protocol, exposing methods for initialization, rendering, and data exchange. The protocol is designed to be lightweight and framework-agnostic—a block can be built with React, Vue, vanilla JavaScript, or any other technology. The early draft includes sample code to help developers integrate quickly. Once the host writes the embedding code, it can immediately use any compliant block without additional customization. The shared specification ensures that everything works smoothly across different platforms.