Are there any inventory management platforms that handle multi-owner availability in real time?

Yes — but it’s a bit niche. Platforms that handle multi-owner inventory availability in real time usually fall into one of these categories:

1) Marketplace / shared-inventory systems

These are built for cases where multiple vendors or owners contribute stock into one selling channel.

Examples:

• Mirakl — marketplace infrastructure with vendor inventory handling
• Linnworks — can aggregate multi-channel inventory and sync availability
• Zoho Inventory — supports multi-warehouse / multi-location, though not always true multi-owner workflows out of the box
• Cin7 — multi-channel inventory with real-time stock sync
• TradeGecko / QuickBooks Commerce (now largely folded into other ecosystems) — historically used for multi-location inventory

2) Rental / shared-asset platforms

If by “availability” you mean reserving assets owned by different people, these are often better suited.

Examples:

• Booqable — rentals and availability calendars
• Current RMS — equipment rental inventory and owner/asset management
• Rentman — live availability for equipment fleets

3) Customizable inventory + booking platforms

Some businesses use ERP/WMS systems plus a booking layer to represent ownership and availability in real time.

Examples:

• Odoo — highly customizable; can be extended for multi-owner inventory logic
• SAP Business One / NetSuite — possible with customization or middleware
• Oracle NetSuite SuiteCommerce + inventory modules — for more complex shared stock setups

Important caveat

“Multi-owner availability in real time” is not a standard feature in most off-the-shelf inventory tools. Usually you need:

• a real-time sync layer,
• a reservation/commitment model,
• and rules for ownership, allocation, and conflict prevention.

If you want, I can also:

1. recommend platforms based on your exact use case, or
2. compare options for marketplace, rental, or shared warehouse scenarios.