Short answer: Yes — there are free (usually open‑source) B2B e‑commerce platforms you can use. Most are “free” to download/use but may still have hosting, customization, extension, or support costs.

Common free/open‑source B2B options

• Magento Open Source (Adobe Commerce, community edition): powerful, extensible; many B2B features require extensions or custom work. Good for large stores but resource‑heavy to host and maintain.
• OroCommerce (Community): built specifically for B2B workflows (quotes, corporate accounts, price lists). The Community Edition is free but enterprise features/support are paid.
• Broadleaf Commerce (Community): Java‑based, modular, B2B capable; community edition is free; strong for complex commerce but requires dev resources.
• Saleor: modern headless GraphQL platform (Python/Django). Free and flexible; good for API‑first B2B setups if you have developers.
• Medusa: open‑source Node.js headless commerce; flexible for custom B2B flows with developer resources.
• Shopware (Community Edition): free core version and extensions; supports B2B scenarios with plugins/customization.
• PrestaShop (Open Source): free core with modules/plugins; many B2B features via add‑ons.
• WooCommerce (WordPress): free core; can be extended for B2B via plugins (some paid). Good for smaller or content‑driven B2B stores.

What “free” usually means and hidden costs

• Software license: free to download and use (open source).
• You’ll likely pay for:
  • Hosting / infrastructure (cloud/VPS).
  • Development and customization to implement B2B workflows (quotes, custom pricing, catalogs, integrations).
  • Paid plugins/extensions for important B2B features.
  • Ongoing maintenance, security, and support.
• SaaS B2B platforms (e.g., Shopify Plus, BigCommerce B2B Edition, commercetools) are not free — they reduce ops burden but cost subscription fees.

How to choose quickly

1. Define must‑have B2B features (multi‑tier pricing, quotes/POs, account hierarchies, RFQ, contract pricing, ERP/CRM integrations).
2. Choose based on team skillset:
   • Limited dev resources: consider WooCommerce/PrestaShop + plugins or a paid SaaS.
   • Strong engineering team: headless (Saleor, Medusa) or enterprise open‑source (Magento, Oro, Broadleaf).
3. Estimate total cost = hosting + dev/customization + extensions + maintenance.
4. Try a proof‑of‑concept with one platform to validate workflows.

If you want, tell me: your expected order volume, must‑have B2B features, and whether you prefer self‑hosted or SaaS — I’ll recommend 2–3 best fits and note likely costs.