.FAS File Extension

Compiled Fast-Load AutoLISP File

Developer Autodesk
3.8  |  17 Votes

What is a FAS file?

Compiled script written in AutoLISP, a variation of the LISP programming language used specifically for the extension of AutoCAD software; often used for creating macros that automate common processes within AutoCAD; can be used for distributing utilities that add new features to the software.

More Information

FAS files are commonly compiled using Visual LISP, an IDE that is included with some AutoCAD purchases.

Open over 400 file formats with File Viewer Plus.Free Download

Programs that open FAS files


FASTA Sequence File

Developer David J. Lipman and William R. Pearson
3.2  |  6 Votes

A FAS file may also be a plain text file saved in the FASTA format, a file format used for storing nucleic acid and protein sequences. It contains one or more sequences, which include a sequence identification code and the sequence. Biochemistry students, academics, and professionals may use FAS files to store and process bioinformatics information, such as the genomes of different species.

More Information

Screenshot of a .fas file in GSL Biotech SnapGene 6
FAS file open in GSL Biotech SnapGene 6

David J. Lipman and William R. Pearson created the FASTA format and released it in 1985. It has since become a standard format for transferring sequences between applications because of its simplicity.

The FASTA format

The FASTA format is simple, consisting of the following elements:

  1. A line beginning with the > character, then followed by a sequence identification code. A text description of the sequence may follow the code, but this is optional, and the DNA software may ignore it.
  2. The next line is the sequence itself, which may be more than one line.

NOTE: FAS files may be saved with other file extensions, such as .fasta (.FASTA files) and .fa (.FA files), but they are saved in the same FASTA format.

How to open a FAS file

You can open an FAS file with various DNA applications, such as GSL Biotech SnapGene (multiplatform), Genome Compiler (multiplatform), and Heracle BioSoft DNA Baser (Windows). To open an FAS file with SnapGene, select File → Open Files....

Opening an FAS file with a text editor

FAS file open in Apple TextEdit 1
FAS file open in Apple TextEdit 1

Since FAS files are saved in plain text, you can also open them with a text editor, such as Microsoft Notepad (Windows) or Apple TextEdit (Mac), or a source code editor. Keep in mind that a text editor or source editor will not display the sequence in the FAS file natively like a DNA app. Also, you may need to rename the .fas file extension to .txt for the text editor to recognize it.

When opened in a text editor or source code editor, you can modify the properties of the FAS file, including the sequence. However, if you incorrectly edit the file, you may corrupt the sequence.

How to convert a FAS file

Several applications, including GSL Biotech SnapGene and Heracle BioSoft DNA Baser, can convert FAS files to other formats.

For example, SnapGene can convert FAS files to the following formats:

  • .DNA - SnapGene DNA File
  • .SEQ - DNA Sequence Text File
  • .EMBL - EMBL Sequence Data File
  • .GBK - GenBank Data File
  • .TXT - Plain Text File
  • .JPG - JPEG Image
  • .PNG - Portable Network Graphic
  • .SVG - Scalable Vector Graphics File
  • .PDF - Portable Document Format

Programs that open FAS files


QuickSilver Fast Save Lisp File

Developer BroadVision
3.3  |  3 Votes

Compiled Lisp (.LSP) file saved in the "Fast Save Lisp Format" by Interleaf or QuickSilver; contains compiled code that can be executed by the program; may be generated by selecting either the DTK→Compile→Buffer or DTK→Lisp→Compile menu commands.

More Information

FAS files are also called FASL (Fast Load) files.

NOTE: BroadVision acquired Interleaf in January 2000 and later renamed the InterLeaf software to QuickSilver. Aurea later acquired BroadVision.

Programs that open FAS files

BroadVision Interleaf 6 and later
BroadVision Interleaf 6 and later

Verified by FileInfo.com

The FileInfo.com team has independently researched all file formats and software programs listed on this page. Our goal is 100% accuracy and we only publish information about file types that we have verified.

If you would like to suggest any additions or updates to this page, please let us know.