What is the .bimlyte format?

Quick answer: A .bimlyte file is a single-file package that stores an entire Bimlyte project — IFC models, BCF issues, saved views, selections and viewer settings — so the project can be reopened exactly as it was left, not merely imported as a model or an issue list. It can be password-protected, and the recipient needs no BIM software and no account: it opens in the browser. Use it to back up a project, move it to another device, or hand a whole coordination session to someone else. Use IFC or BCF instead when the recipient needs the model or the issues in a tool other than Bimlyte.

IFC and BCF are designed to exchange specific parts of a BIM workflow. IFC carries the model, while BCF carries the issues and comments connected to it. Neither format is meant to recreate an entire Bimlyte project exactly as it was left.

That is what the .bimlyte format is for.

A .bimlyte file is a complete, single-file backup of a project. It keeps the original models, coordination data, saved views, selections and viewer settings together, so the project can later be restored as a working Bimlyte workspace — not merely reopened as a model or issue list.

Why was the .bimlyte format introduced?

A live coordination project contains more than its exported files. It may include several IFC models, BCF issues from different sources, saved camera positions, colour schemes, visibility filters, section planes, measurements and annotations.

Some of that information belongs in IFC or BCF. Some of it exists only as part of the working environment created inside Bimlyte.

Without a dedicated project format, creating a backup would mean exporting several separate files and still losing part of that environment. The .bimlyte format was introduced to preserve everything in one operation.

This is why export is deliberately all-or-nothing. BCF, PDF and Excel remain the right formats for sharing selected information. A .bimlyte file is intended for backup, archiving or transferring the complete project.

What does a .bimlyte file contain?

The file stores a direct snapshot of the project’s live local records rather than rebuilding them into a simplified BCF package.

It includes:

• BCF data with comments, viewpoints and original source data retained for later re-export where available;
• the original IFC files in full;
• saved views, including camera position, visibility, colours, clipping planes, measurements, annotations and snapshots.

This means the file preserves not only the source material, but also the context created during review. A prepared colour scheme, hidden-element setup or saved section can represent real coordination work. Restoring only the IFC model would lose that work.

What is not included?

Bimlyte does not store the temporary IFC cache used to display models efficiently in the browser, such as processed geometry, edges and derived metadata.

Those files can be rebuilt from the original IFC, so including them would make the backup larger without preserving any unique project information. During import, Bimlyte recreates them automatically.

The principle is simple: .bimlyte saves what would otherwise be lost and rebuilds what can be calculated again.

How is the file protected?

Every .bimlyte file is encrypted with AES-256-GCM using the cryptographic functions built into the browser. This protects the project contents and also checks their integrity. If the encrypted data is damaged or modified, Bimlyte refuses to import it rather than attempting to load an unreliable project.

A new encryption key is created for every exported file. That key is then protected in one of two ways.

 

Without a password

Password protection is optional and disabled by default. Without a password, the file is still encrypted, but it can be unlocked by the Bimlyte application. This prevents casual inspection as an ordinary ZIP archive, but it should not be treated as strong protection from someone who has both the file and access to Bimlyte.

 

With a password

For confidential projects, a password should be added during export. The unlocking key is then derived from that password using PBKDF2-SHA256 with 600,000 iterations and a fresh random salt.

The password is not stored in the file, and no application key, support override or recovery key is added. As a result, nobody can open the project without the password — including Bimlyte support.

That also means a forgotten password cannot be recovered. The application requires at least eight characters, but does not force an arbitrary mixture of capitals, numbers and symbols. A long, memorable passphrase is usually the better choice.

Where does .bimlyte fit in a BIM workflow?

Use IFC when another tool or team needs the model. Use BCF when they need coordination issues. Use PDF or Excel when they need a readable report.

Use .bimlyte when you need the complete Bimlyte project: for backup, archiving, moving work to another device or handing the full workspace to a colleague.

The entire process remains local. Export, encryption, decryption and import happen in the browser on the user’s device. No account or sign-in is required, and project files are not uploaded to a server.

Because the archive is assembled and processed in memory, the practical size limit depends on the computer’s available resources.

The .bimlyte format does not replace IFC or BCF. It solves a different problem: IFC and BCF help project information move between tools; .bimlyte preserves the complete Bimlyte workspace so it can move with you.

Read IFC vs BCF: what’s the difference? to see how the two open exchange formats work together, or open Bimlyte to create and back up a project entirely on your own device.