How BigXL Protects Sensitive Data on Your Device
BigXL works on a private copy of each file, kept in a folder only your account can read and deleted when you close the file. You can clear every copy at any time, and you can turn on encryption for working copies in Settings; an organisation can require it. Saved sessions, settings and stored secrets are always encrypted. Files you export are normal files, so protect them with your device and organisation's usual controls.
Sensitive spreadsheet work should not have to leave your computer just to be opened or cleaned. But keeping a file local is only part of the privacy story: desktop apps also create databases, temporary files, caches, and saved workspaces as they work.
Here is what BigXL creates on your device, how long it lasts, and where the boundary is.
Your working copies stay private and short-lived
So that very large files open and sort quickly, BigXL reads each file once into its own working copy. Your original file changes only when you choose Save, and the first time BigXL keeps a copy of it beside the file. The copies live in a private folder that only your operating-system account can read.
A copy is deleted when you close its file. Copies from an earlier session are removed the next time BigXL starts, unless you asked BigXL to reopen those files. You can see how much space the copies use, and clear them all, in Settings, Privacy.
Encryption, when you want it
Your original file is already on the same computer, readable by your account, and the strongest protection for both is full-disk encryption such as FileVault or BitLocker, which most business computers already use. So BigXL leaves working copies unencrypted by default and keeps big files fast.
If your organisation requires it, turn on Encrypt working copies in Settings, Privacy. From then on, the copies, their temporary spill files and caches are encrypted with a key BigXL keeps in a private file in its own data folder, so a copy that is backed up or left behind cannot be read on its own. An organisation can switch this on for everyone through its policy file. Very large files take about twice as long to open with it on.
BigXL always encrypts its small saved state: the automatic workspace, saved sessions, settings, notes, and stored secrets such as your licence key.
Exports remain files you control
When you choose to export a result as CSV, Excel, JSON, or another format, BigXL writes a normal file to the location you selected. That is intentional: the result must remain usable in other tools and shareable with colleagues. Once exported, it is your copy to protect with your device, storage, and organisation’s sharing rules.
When replacing an existing export, BigXL keeps a temporary encrypted recovery copy while the replacement is in progress. If the app stops unexpectedly, it can restore the prior file when it starts again. This does not encrypt the completed export.
What this does not promise
Encryption at rest is not protection from every threat. It does not stop malware running as your account, someone using your unlocked computer, screenshots, or data you choose to export. Deleting a file cannot guarantee that every physical copy is erased from an SSD, a snapshot, or a backup. Full-disk encryption, a locked device, and sensible backup retention remain the protections that matter most.
For a privacy-sensitive workflow, keep the original file in an approved location, do the work locally, review what you export, and share only the output people need.
Common questions
Does BigXL upload my spreadsheet?
No. Everything happens on your computer. Your original file stays where you saved it, and BigXL changes it only when you choose Save, keeping a copy of the original the first time.
Where are BigXL's working copies, and how long do they last?
In a private folder only your operating-system account can read. A copy is deleted when you close its file, copies left from an earlier session are removed the next time BigXL starts, and Settings, Privacy, Clear working copies removes all of them at once.
Are working copies encrypted?
When you turn on Encrypt working copies in Settings, or your organisation requires it. It is off by default because your original file is already on the same computer, and full-disk encryption such as FileVault or BitLocker protects both. Encrypted copies take about twice as long to make on very large files.
Which BigXL files are always encrypted?
Saved workspaces and sessions, settings, notes and stored secrets such as your licence key. They are small, so encrypting them costs nothing.
Are exported CSV and Excel files encrypted?
No. A file you choose to export is a normal CSV, Excel, JSON, Parquet, or other deliverable so you and your colleagues can use it. Store and share that file using your organisation's approved protections.
Will BigXL ask me for a password?
No. When encryption is used, BigXL creates its key the first time it runs and keeps it in a private file in its own data folder. You never create, type, or remember a password.
Does deleting a BigXL working copy securely erase it?
No. Ordinary deletion cannot guarantee erasure from SSD wear-levelled blocks, snapshots, or backups. Full-disk encryption and appropriate backup controls remain important.