Vendoo
One inventory list that crossposts and syncs sales, including Whatnot (beta)
Best crosslisting apps for Whatnot (2026)
Updated 2026-11-06
These are the published listing tools in our directory that can get inventory onto Whatnot from another channel or a single form. None is Whatnot-only, and none claims an official Whatnot API on its own site. They are ordered by how directly their official pages document Whatnot support, not by a paid placement.
Prices are as of 2026-11-06 and can change; confirm on each maker's site.
Help center documents Whatnot import, crosslisting and sale detection, though it labels Whatnot as beta and sale detection needs your computer on. Starter is $14.99/mo; iOS, Android and web apps.
Crosslist
Universal listing form that publishes to many marketplaces
Integration page describes connecting Whatnot and publishing to it from one universal listing form. Plans run $29.99 to $44.99/mo by listing volume, with an unlimited top tier.
Sidekick Tools (formerly Posh Sidekick)
Automation bots and crosslisting for Poshmark, Mercari and Whatnot
Cross-posts to seven marketplaces including Whatnot and adds a Whatnot Bot for follows, follow-backs and relisting. Cross Posting plans run $9.99/mo (100 cross-posts) to $44.99/mo (1,000).
Underpriced AI
Photo-to-listing pricing tool with a free extension for Whatnot forms
Best for pricing and listing copy on single items: Whatnot works only through its free browser extension, which fills the listing form on your computer. Subscription from $5/mo, plus scan packs.
At a glance
| App | Pricing | Platforms | Official Whatnot API |
|---|---|---|---|
| Vendoo | From $14.99/mo | Web, iOS, Android | Not listed |
| Crosslist | From $29.99/mo | Web | Not listed |
| Sidekick Tools (formerly Posh Sidekick) | From $9.99/mo | iOS, Android, Web | Not listed |
| Underpriced AI | Free plan · from $5/mo | Web, Chrome extension, iOS, Android | Not listed |
Prices checked by hand and may change; confirm on each maker's site.