Persefoni vs Watershed

Verdict

Persefoni and Watershed are the two carbon accounting platforms most often shortlisted together by mid-market and enterprise teams building a Scope 1, 2 and 3 inventory for regulatory disclosure. Both calculate emissions from existing business data, map results to CSRD, ISSB and CDP, and are built for audit-ready reporting rather than a quick estimate. The practical difference is entry point and depth: Persefoni will let a single person run a real inventory for free before anyone signs a contract; Watershed's strength shows up later, in supplier engagement at scale and in what happens after the inventory exists.

Persefoni's free PRO plan covers a single user on an annual calculation cycle, with an AI Copilot to help with data mapping and factor selection — a real way to see the platform's data model before committing budget, not a stripped-down demo. Its paid Advanced tier adds unlimited users, custom calculation frequency and decarbonization scenario modeling. Watershed has no published free tier; its differentiators are a supplier engagement portal built for collecting primary supply-chain data at scale, disclosure coverage that extends to the US SEC climate rule (not just CSRD/ISSB/CDP), and a carbon removal credit marketplace for companies ready to purchase verified removals against their targets.

Choose Persefoni if

• You want to run a real, standards-aligned inventory on a free tier before any procurement conversation starts.
• A single user or small team will own the inventory, at least initially.
• You need an AI-assisted starting point for data mapping and factor selection.

Choose Watershed if

• Scope 3 is dominated by suppliers you need to engage directly for primary data, not spend-based averages.
• You file with the US SEC and need climate-rule-aligned disclosure alongside CSRD and CDP.
• You expect to fund verified carbon removals as part of your reduction program and want that built into the same platform.

The honest caveat

Neither vendor publishes list pricing beyond Persefoni's free tier, so the real cost comparison only happens inside a quote — the free tier is useful precisely because it lets you evaluate Persefoni's data model without waiting for that quote, while Watershed offers no equivalent trial path from public information. If your Scope 3 footprint is simple and supplier engagement is not a near-term priority, that difference in depth may not be worth paying for; start with Persefoni's free tier and see whether you actually need what Watershed adds before assuming you do. For broader category context, see how to choose a carbon accounting tool.