Opening a FASTQ File

The FASTQ file type is primarily associated with FastQC.

FASTQ	File extension: FASTQ
	File type:	text file

What is a FASTQ file?

FASTQ files mostly belong to FastQC.

FASTQ files are text-based files that hold DNA sequence data and the associated quality scores. They are produced by sequencing platforms such as Illumina MiSeq and accessed through databases like NCBI or referenced in documentation on FASTQ.
Each record in a FASTQ file usually consists of four lines:

Header: Contains an identifier for the read.
Sequence: Lists the nucleotides (A, T, C, G) determined by the sequencer.
Separator: Often a single '+' character, sometimes followed by the identifier.
Quality Scores: Provides a score for each nucleotide, encoded in ASCII to represent base call accuracy.

This structure enables fast parsing and is integral for downstream processes like alignment, variant calling, and quality control using tools such as FastQC. The files may also be compressed (e.g., using GZIP) to manage large volumes of sequencing data.
FilExt.com note: Users can open a FASTQ file with a text editor for a quick look, but specialized bioinformatics software is often preferred for analysis.

How can I open a FASTQ file?

You need a suitable software like FastQC to open a FASTQ file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your FASTQ file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a FASTQ file directly in the browser:. Just drag the file onto this browser window and drop it.

Online FASTQ Text Viewer

Choose your .fastq file to view

or drag and drop it here

Online File Viewer

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How to extract texts from FASTQ files or capture a screenshot to PDF, JPG, DOCX, TXT, ...

You can extract texts from FASTQ file or capture a preview screenshot using our online FASTQ file viewer:

To do so, click the "Choose your .fastq file to view" button above.
After your file is opened in browser,
click "Save as..." in the menu.
Then choose the file format (e.g. JPG, PDF, DOCX, TXT, ...) you want.
Download the converted file.

Programs that open and convert FASTQ files:

FastQC
See the previous paragraphs to learn more about the main application. FASTQ files are often referred to as FastQC data files because this type of file is primarily created or used by this software.
MAQ
FASTQ files are text files containing sequence data which can be accessed using the MAQ software application. FASTQ is a text-based format designed for the purpose of storing biological sequence, which is usually represented as an ASCII character. It’s often utilized for storing nucleotide sequences. There are several variants of FASTQ in use as the format itself is not standardized.

FASTQ file format details:

Every file has a defined file format, i.e. how the data is arranged in the file. The first characters in a file identify the file format, for example, HTML files start with the bytes <html>. However, different programs can use the same file extension, and file extensions can be assigned incorrectly. So you need a detailed analysis of a file to find out the format and the associated program. In the following you will find our evaluation of the FASTQ files:

The FASTQ file extension is quite common and is used by a few programs, each with its own file format. The two most common formats are as follows:

25% of all FASTQ files start with the magic bytes 40 4D, which are always the first bytes of this file format. If you open these files in a text editor, you can view and read the content yourself. Most of these files are 2 MB to 300 MB in size. The file type was developed only in the last few years. These files are often associated with sample, undetermined and reads.
20% of all FASTQ files start with the magic bytes @A0, which are always the first bytes of this file format. The contents of these files can even be read by a human. Most of these files are 84 MB to 9 GB in size. Certain words are almost always found in the files, such as 1000 1. Files like these are sometimes connected to extended, frags, combined, control and ncgm.

All the rest of the FASTQ files (55%) have different formats, such as GZIP and GWNJ. Sometimes used for filt, user, hjchtbgxk, xpress, pass, phages, data or meta. If you want to find out what your FASTQ file contains, drag and drop it onto this page.

Technical Data for FASTQ File Extension

File classification:

Data

Related files:

fasta, fa, fq, sam, bam, vcf, sra, gz, seq, sit, zip, fna, fast5, cbc, txt, ab1, bgx, 1, tar, qz, hist, ngs, md5

Mime type:

text/plain

a fastq text file is a special file format and should only be edited and saved with the appropriate software.

How to solve problems with FASTQ files

Associate the FASTQ file extension with the correct application.
Update your software that should actually open text files. Because only the current version supports the latest FASTQ file format. Search, therefore, e.g. on the manufacturer website after an available FastQC update.
To make sure that your FASTQ file is not corrupted or virus-infected, get the file again and scan it with Google's virustotal.com.
Click here to open your .FASTQ file online - secure, fast, and no downloads needed.