What is the TSV file format?
.tsv files are of an uncomplicated structure, because they are based on plain text. They are used to store data arranged in the form of tables - for instance, records from a database or a spreadsheet. Within a .tsv file, each column of data is separated from the next by a horizontal tab character (0x09). Each line of a .tsv file represents one row of the table.
.tsv files can be imported, processed and exported with most spreadsheet applications, including Microsoft Excel, LibreOffice Calc and Google Sheets. The raw data can also be opened in any plain-text editor, since no special software is required to read the format. .tsv is commonly used to transfer tabular data from one program into another - for example, from a spreadsheet into a database application - and is a standard interchange format in bioinformatics pipelines.
.tsv files are a well-established alternative to the popular .csv files. The two formats differ in the delimiter used to separate columns: within a .csv file, columns are divided by a comma. However, commas frequently appear inside text fields, which can cause parsing errors when the file is interpreted by the target program. Tab characters are rarely used within text fields, so a .tsv file is less prone to misinterpretation and typically does not require fields to be quoted. Files with an identical structure are sometimes saved with the .tab extension instead.
The MIME type for .tsv is text/tab-separated-values, registered with IANA in 1993. .tsv has no binary magic number; parsers recognize the format by its tab-separated structure.
Security & safety
RISK: MEDIUMTSV is plain text and can't run code by itself, but it shares CSV's formula-injection risk: if a cell's value starts with =, +, - or @, a spreadsheet may execute it as a formula when the file is opened, which attackers exploit to run commands or exfiltrate data. Modern Excel and LibreOffice warn before running such formulas - don't enable them in files from untrusted sources. The everyday risk, though, is data corruption rather than malware: a wrong encoding garbles non-Latin text, and a real tab or newline accidentally sitting inside a value can shift later columns.
Format details
in a nutshellPrograms that open TSV files
Windows4 apps
Microsoft Excel
Paid Open the .tsv directly (Excel auto-splits on tabs), or for tricky encodings use Data > 'From Text/CSV' and pick UTF-8 / Tab delimiter in the preview. 
Windows Notepad
Built-in Quick read-only peek at the raw text; tabs show as spacing. Fine for small files, no column alignment. 
LibreOffice Calc
Open-source Open the TSV - Calc's import dialog lets you tick 'Tab' as the separator and choose the character set. The most reliable free TSV opener. 
Notepad
Open-source Open as text to inspect raw rows, check encoding, and view tab stops (View > Show Symbol shows the tabs). 
macOS3 apps
Microsoft Excel
Paid Open the .tsv (auto-splits on tabs) or use File > Import for control over delimiter/encoding.
LibreOffice Calc
Open-source Open the TSV and set Tab as the separator and the character set in the import dialog. Free and reliable. 
Numbers (Apple)
Free Double-click to open the TSV; Numbers detects the tab delimiter and shows encoding options on import. 
Linux2 apps
LibreOffice Calc
Open-source Open the TSV; the import dialog lets you choose 'Tab' separator and the encoding. The default choice on Linux.
GNOME Gnumeric
Open-source Lightweight spreadsheet with a clear text-import assistant for tab delimiter and encoding. 
Google Sheets
Free File > Import > Upload the .tsv and choose 'Tab' (or auto-detect) as the separator. Handles UTF-8 well, runs in the browser. Technical details
deep spec| Field delimiter | Horizontal tab (U+0009 / 0x09) |
| Record delimiter | LF (0x0A) per IANA spec; CRLF (0x0D 0x0A) widely accepted in practice |
| File encoding | No in-file encoding declaration; UTF-8 is the modern default; legacy files may use ASCII or locale-specific encodings |
| Byte-order mark | Optional UTF-8 BOM (EF BB BF) permitted; many parsers strip or ignore it on read |
| Magic bytes | None - the format has no binary signature; identified by tab-separated row structure |
| MIME type | text/tab-separated-values |
| Header row | Optional; first line conventionally lists column names |
| Field quoting | No mandatory quoting standard; some parsers allow double-quoted fields containing embedded tabs or newlines |
| Empty fields | Represented by two consecutive tab characters (e.g., value1\t\tvalue3 means an empty middle field) |
| Column limit | None defined by the format; application-dependent (Microsoft Excel supports up to 16,384 columns) |
| Row limit | No format-defined limit; constrained by available memory and the importing application |
| Alternative extension | .tab - identically structured files are interchangeably saved with this extension |
| Primary use cases | Database and spreadsheet data export, bioinformatics data exchange (BLAST output, genome annotation), ETL pipelines |
| Quoting requirement | Rarely needed, because tab characters seldom appear in text fields - a practical advantage over comma-delimited formats |
| Released | Tab-delimited text in use since the 1980s; IANA media type registered 1993 |
| Open standard | Yes · royalty-free |
| Specification | www.iana.org |
TSV conversions
Community Q&A
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