ReflexGrid is a spreadsheet that runs in the browser, made for workbooks that have to keep working as they do in Microsoft Excel:

• Excel files in, Excel files out: real .xlsx and .xlsm (formulas, styles, tables, charts, conditional formats, validation, the VBA project), and CSV or TSV.
• Excel VBA macros in the browser: a VBA editor, MsgBox and InputBox, event macros such as Worksheet_Change, VBA functions in formulas, and UserForms with a form designer. Macros run on the server, in a sandbox. Excel for the web can’t run VBA; ReflexGrid can.
• Edit together, live: share a workbook’s link; everyone sees changes at once and each other’s selections, and undo takes back only your own changes.
• A Python spreadsheet engine: gridcore calculates 478 Excel functions, with dynamic arrays and LET/LAMBDA, and runs VBA macros headless, with no Excel installed.
• Self-hosted, MIT-licensed.

Videos

• Co-editing, VBA macros and UserForms, the latest demo (October 2026): English (3:20) · 中文 (3:41)
• Introduction to the first version (October 2026, 1:51): watch
• DDNS Intent (October 2026, 2:21): how apps on re_ddns open each other, which is how ReflexGrid’s Call everyone works: watch
• Agentic App Store demo (July 2026, 16:44): the re_ddns App Store, which installs ReflexGrid with sign-in and calls: watch

Try it

With Python 3.11 or newer and Poetry:

git clone https://github.com/milochen0418/reflex_grid.git
git clone https://github.com/milochen0418/reflex_ddns_auth.git
cd reflex_grid
poetry install
poetry run ./reflex_rerun.sh        # then open http://localhost:3000

Read more

• README: every feature, how it compares with ONLYOFFICE, Collabora Online, Univer, Grist, Excel for the web and Google Sheets, and the FAQ
• Excel macros (VBA) in ReflexGrid: how macros and UserForms run, the sandbox, checks against Excel, limits
• Excel compatibility report: the latest test results by area, compared with answers recorded from Microsoft Excel
• Architecture: the engine’s layers, commands, undo, recalculation and collaboration