VS Code (Windows, macOS, Linux) — Free and Open Source with a nice GUI. Edited a 3.6 GB JSON file, loaded in a minute. You must have enough RAM to load the files.
Free read-only viewers:
- glogg (Windows, macOS, Linux) – Confirmed to handle multi-GB files. Its main feature is regular expression search. Has tabs, reads files directly from disk, can watch/follow files, and allows user to mark lines.
- LogExpert (Windows) – «A GUI replacement for
tail.» Supports file following, searching, filtering, configurable highlighting, plugins, and external tools. - Large Text File Viewer (Windows) – Minimalist and has very small executable size. Supports split view, text theme customization, regex search, and file following.
- Lister (Windows) – Even more small and minimalist. It’s one executable, barely 500 KB, but it still supports searching (with regexes), printing, a hex editor mode, and settings.
Free editors:
- Vim and Emacs (Windows, macOS, Linux) – Classic Unix editors. Steep learning curve, but brutally efficient. They have settings that can be tuned to make them even faster.
- Large File Editor (Windows) – Opens and edits TB+ files, supports Unicode, uses little memory, has XML-specific features, and includes a binary mode.
- HxD (Windows) – A hex editor, not a text editor; but it’s amazingly fast and useful.
- GigaEdit (Windows) – Supports searching, character statistics, and font customization. But it’s buggy – with large files, it only allows overwriting characters, not inserting them; it doesn’t respect LF as a line terminator, only CRLF; and it’s slow.
Builtin programs (no installation required):
- less (macOS, Linux) – The traditional Unix command-line pager tool. Lets you view text files of practically any size. Can be installed on Windows, too.
- Notepad (Windows) – Decent with large files, especially with word wrap turned off.
- MORE (Windows) – This refers to the Windows
MORE, not the Unixmore. A console program that allows you to view a file, one screen at a time.
Web viewers:
- htmlpen.com – Can open and syntax-highlight TB+ files. Allows editing, except for very large files. Supports searching, regexes, and exporting.
- readfileonline.com – Another HTML5 large file viewer. Supports search.
Paid editors:
- 010 Editor (Windows, macOS, Linux) – Opens giant (as much as 50 GB) files.
- SlickEdit (Windows, macOS, Linux) – Opens large files.
- UltraEdit (Windows, macOS, Linux) – Opens files of more than 6 GB, but the configuration must be changed for this to be practical: Menu » Advanced » Configuration » File Handling » Temporary Files » Open file without temp file…
- EmEditor (Windows) – Handles very large text files nicely (officially up to 248 GB, but as much as 900 GB according to one report).
And finally, have you tried opening the large file with your regular editor? Some editors can actually handle reasonably large files. In particular, Notepad++ (Windows) and Sublime Text (Windows, macOS, Linux) support files in the 2 GB range.