BLK File

What are BLK files and how to open them

Are you having problems opening a BLK file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your BLK files.

What is a BLK file?

BLK files have multiple uses, and AutoCAD Block Template is one of them. Read more about the other uses further down the page.

AutoCAD Block Template File

These files contain block templates for use when exporting a project in AutoCAD. AutoCAD is a 2D and 3D Computer-Aided Design (CAD) software. Project data can be exported into different formats, and block templates define the export properties of each block, like which blocks must be included in each output format.

How to open BLK files

We have identified one BLK opener that is compatible with this specific type of BLK file.

Programs that open AutoCAD Block Template files

Last updated: August 24, 2026

All known file formats using extension .BLK

While AutoCAD Block Template File is a popular type of BLK-file, we know of 4 different uses of the .BLK file extension. Different software may use files with the same extension for different types of data.

Lightscape Block

Lightscape Block files store libraries of reusable 3D objects (called blocks) and lighting fixtures (luminaires) used by Lightscape during the model setup stage in lighting design workflows. These files are created by Lightscape when saving a block library: the blocks may include geometry, light source definitions, surface and material properties, insertion (origin) points, and photometric data. Blocks provide a way to reuse model components - once a block is defined, multiple instances can be placed in a scene; changing the block definition updates all its instances. Luminaires are blocks with additional photometric attributes that control light emission from fixtures.

Lightscape Block libraries are used during the Preparation phase: designers group surfaces or other blocks into block definitions, assign materials and lighting properties, and then export selected blocks and luminaires into a .blk file. These library files can later be loaded back into Lightscape projects via the Blocks table, allowing the user to import geometry, materials, lights, and luminaires into new or existing scenes. When a block is defined as a luminaire, existing instances inherit the photometric properties and light fixture behavior.

Internal structure of a Lightscape Block file is in plain (ASCII) text. It begins with an ASCII signature at offset 0: ".BlockTable: ". File contents include sections labelled LIGHTSCAPE ATTRIBUTE TABLE, SOURCE TABLE, BLOCK TABLE, LAYER TABLE, and others. Keywords found include ABSORPTION COEFF, REFRACTION INDEX, TEMP ATTR TABLE, FOCUS POINT, LIGHT UNITS, BASE POINT, SUB FACTOR, PLANE EQ, SPECULAR, DIFFUSE, POLYGON, ENTITY, FLAGS, GLOW, K_DR, K_DT, K_SR, K_ST, PNT1 through PNT4, and TABLE END.

While we have not verified the apps ourselves yet, our users have suggested ten different BLK openers which you will find listed below.

Quilt Block File

Quilt-Pro is a quilt design software that enabled you to draw pieced quilt blocks, applique blocks, quilting stencils, and foundation blocks.

BLK opener for Windows

We have identified one BLK opener that is compatible with this specific type of BLK file.

Sequencer One Audio Block File

Sequencer One is an audio sequencer by Gajits Music Software, made for the Commodore Amiga home computer.

Various apps that use files with this extension

These apps are known to open certain types of BLK files. Remember, different programs may use BLK files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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