From CSV to a working project.
Jason is designed to be direct: choose the file, let the first import finish, then work from the local project.
Open a source CSV
Choose a CSV from Jason. The browser reads the source and creates a local project. Keep the tab open until the first import reports completion.
Work from the project
Search and sort the full dataset, edit values, and add supported calculations. Only the visible grid surface is rendered at once.
Reopen without reimporting
Return to the local project on the same browser profile and device. Clearing site storage also clears local Jason projects, so retain the source and important exports.
Export the result
Export back to CSV when the work is complete. Treat the export as a new file and validate it before replacing any source data.
Try it on the file you gave up on.
Open a CSV that your spreadsheet app refuses. Free covers files up to 1 GB and three local projects.