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Comparison chart with key features:
| Using | Plugin | Math Formulas | Inline Editing | Works in Mobile | Auto-numbering | Comment |
|---|---|---|---|---|---|---|
| Spreadsheets for Confluence |  |  | | | n/a | |
| Yes | Bob Swift Advanced Tables |
| | | | Like the most but requires math functionality. |
| Yes | Excellentable | | | | (as far as I can tell) | Nice search function but ugly. |
| No | Spreadsheets for Confluence | | | | | n/a |
Encryption
Looks promising, no public key, but simple enough - https://marketplace.atlassian.com/plugins/com.prcpo.confluence.plugins.secure-content-block
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