| App | One-time price | Platforms | License | Free tier | Same platform |
|---|---|---|---|---|---|
| Postbox(this app) | $49 one-time | Mac, Windows | License not confirmed | No | – |
| Kanmail | Free tier, $49 one-time | Linux, Mac, Windows | License not confirmed | Yes | Yes |
| SmartRSS: RSS Reader & Podcast | Free tier, $19.99 one-time | Linux, Mac, Windows | License not confirmed | Yes | Yes |
| mailbird | Free tier, €49.5 one-time | Windows | License not confirmed | Yes | Yes |
| Sendy | $69 one-time | Web | License not confirmed | No | No |
| Invoice Chase Tracker | €16.99 one-time | Mac, Web, Windows | Perpetual, lifetime updates | No | Yes |
| BoltAi | $19 one-time | Mac | License not confirmed | No | Yes |
| Dot | Free tier, $9.99 one-time | Mac | License not confirmed | Yes | Yes |
| Eagle | $29.95 one-time | Mac, Windows | License not confirmed | No | Yes |
| GoodLinks | $6.99 one-time | Mac | License not confirmed | No | Yes |
| TablePlus | $89 one-time | Linux, Mac, Windows | License not confirmed | No | Yes |
| Xnapper | $15 one-time | Mac | License not confirmed | No | Yes |
| BusyCal | $49.99 one-time | Mac | License not confirmed | No | Yes |
Prices are one-time license fees as listed on each developer's site and may change. Ranked by similarity to Postbox: shared category, tags, platforms and community likes.
Kanmail is the closest pay-once alternative to Postbox. Turn your inbox into a kanban board for organized email management. Integrate Gmail, Outlook, and more into one view. Enjoy color-coded senders and lightning-fast shortcuts for seamless workflow transitions. Pay once, own forever for $49 USD! Secure and private. It costs Free tier, $49 one-time and runs on Linux, Mac and Windows.
Yes. Kanmail, SmartRSS: RSS Reader & Podcast, mailbird and Dot offer a free tier, and each also sells a one-time license if you outgrow it.
GoodLinks is the lowest-priced option at $6.99 one-time, compared with $49 one-time for Postbox. All prices are one-time license fees, not subscriptions.
Yes. Kanmail, SmartRSS: RSS Reader & Podcast, Sendy, Invoice Chase Tracker and TablePlus are available on Linux and Web, which Postbox does not support.
No. Every app on PayOnceApps is listed because it sells a one-time (perpetual) license. Some also offer a free tier or trial. Prices are checked against the developer's site but can change, so confirm on the app's website before buying.
+6 more
+5 more
+7 more
+5 more
+2 more
+4 more
+2 more
+6 more
+4 more
+3 more