Pentagon alternatives
TL;DR: 12 companies doing similar work to Pentagon in B2B, ranked by how closely they match what Pentagon actually does — not just by category.
How this list was built: every company here is Y Combinator-backed and shares at least one category with Pentagon. They are scored on how closely their own description overlaps with Pentagon's, and all facts shown come from the YC company records — nothing is estimated.
What are the best alternatives to Pentagon?
| Alternative | What it does | Batch | Team | Status |
|---|---|---|---|---|
| Snapboard | — | Winter 2020 | 2 | Inactive |
| Insoshi | — | Winter 2008 | — | Inactive |
| Thinkature | — | Summer 2006 | — | Inactive |
| Acunote | — | Winter 2011 | — | Active |
| ZumoDrive | Media in the cloud | Summer 2007 | 15 | Acquired |
| Fithub | — | Winter 2010 | — | Inactive |
| Post.fm | New email inbox. | Summer 2010 | — | Inactive |
| OneCLI | The open source AI teammates for your company. | Summer 2026 | — | Active |
| Savant | Company brain every AI-native enterprise runs on | Spring 2026 | 2 | Active |
| Retool | Build internal tools fast. | Winter 2017 | 300 | Active |
| ZeroMailer | Easy mailing lists | Summer 2012 | 2 | Acquired |
| Emailio | Email built for wellness | Winter 2014 | 5 | Active |
Is Pentagon still active?
Pentagon is still operating, so switching is a choice rather than a forced migration. Compare on fit and price rather than urgency.
How was this list put together?
Every company here is Y Combinator-backed and shares at least one category with Pentagon. They are then ranked on how closely their own description overlaps with Pentagon's, so the closest matches come first rather than whoever happens to share a tag.