Opening Files

Last modified: June 11, 2025

Types of files

Rowboat can open comma-separated value (CSV) files and tab-separated value (TSV) files.

Rowboat can also open Excel files (.xls and .xlsx). If the file has multiple sheets, Rowboat will ask for the specific sheet that you would like to open.

We also offer a Chrome extension for Google Sheets. Using this extension, you can easily view Google Sheets spreadsheets in Rowboat without having to download the file first. With your spreadsheet open, click the Chrome extension, and your spreadsheet will automatically open up in Rowboat.

File size

Rowboat can currently work with files up to approximately 800 MB, depending on your machine.

Look out for upcoming improvements to memory in the browser, as well as other options for working with larger files.

Encodings

Rowboat does its best to automatically detect the encoding of the file, but it may not always be right. The default encoding is UTF-8, where possible.

To change the encoding of a file, look for the encoding dropdown at the bottom of the app, and choose between the following options:

Column data types

Rowboat distinguishes between the following column data types:

Rowboat does its best to automatically detect column data types. To change the data type of a column, use the data type dropdown in a column to switch to another data type.

Parsing numbers

Rowboat supports basic handling of integer and decimal entries containing the following symbols:

Currency

Rowboat currently detects the dollar symbol ($) and the Euro symbol (€). Negative currency amounts are not supported at this time.

Date and time formats

Rowboat automatically detects the following date and time formats. Additional timestamps formatted in strptime date notation are also supported when manually entered using the “Set Format” option for the column, in the data type dropdown.

Example Format
1972 %Y
11:00:00 AM %H:%M:%S %p
January 2021 %B %Y
Jul 1, 2004 %b %d, %Y
2011-11-07 %Y-%m-%d
12/04/2017 %m/%d/%Y
12/04/17 %m/%d/%y
11/4/2011 11:04 %m/%d/%Y %H:%M
11/4/11 11:04 %m/%d/%y %H:%M
9/1/2012 12:07 AM %m/%d/%Y %H:%M %p
9/1/12 12:07 AM %m/%d/%y %H:%M %p
9/1/12 12:07:03 AM %m/%d/%y %H:%M:%S %p
9/1/2012 12:07:03 AM %m/%d/%Y %H:%M:%S %p
2022-10-10 10:17:45 %Y-%m-%d %H:%M:%S
2022-10-10 10:17:45.59 %Y-%m-%d %H:%M:%E*S
2022-10-10 10:17:45 UTC %Y-%m-%d %H:%M:%S %Z
2022-10-10 10:17:45.59 UTC %Y-%m-%d %H:%M:%E*S %Z
2023-05-30T16:51:36.770Z %Y-%m-%dT%H:%M:%S.%fZ
2023-05-30T16:51:36Z %Y-%m-%dT%H:%M:%SZ
2023-05-30T16:51:36 %Y-%m-%dT%H:%M:%S.%f
2023-05-30T16:51:36 %Y-%m-%dT%H:%M:%S

Certain formats will not automatically be detected, such as %Y on its own, or %Y%m%d, because these cannot be distinguished from numbers that happen to have the same format. To properly parse the latter, you must manually enter %Y%m%d as the format, which will be changed to %E4Y%m%d behind the scenes, specifying a 4-digit year. Years that are three digits (as in AD 476) or five or more digits are also supported by the time parser, so it's necessary to differentiate in the formatting to match properly.

More of these extended formats can be found in the Google BigQuery documentation.

Also note that time formats that use %- syntax are not supported. (They are for formatting without zero padding, so the - syntax is not relevant/useful for parsing.)

Header row detection

Rowboat automatically detects whether a file has a header row. To change this, toggle headers on or off in the bottom bar of the app.

Rowboat does not currently support files with multiple header rows. Additional rows can be deleted by hiding rows.