Best Carbon Accounting Software in 2026
Updated
In short: Carbonfact is ranked #1 of 29 as of 4 October 2026, ahead of CarbonTool and Greenio. The best-ranked option with a free plan is CarbonTool. The lowest first paid tier on this page is CarbonAnalytics at £69.99/mo.
Carbon accounting software is for organizing emissions information and supporting the work of tracking it across an organization and its suppliers. The ranking opens with Persefoni, Carbonfact, and ACT Group Decarbonization Platform. Compare their stated scope coverage, data collection, and emissions factors, then look at audit trails and API access for information on records and integrations. Supplier engagement is another dimension to weigh if your process involves working with suppliers. Free-plan availability and paid-from pricing provide cost context alongside those capabilities. Consider which emissions data and supplier-related tasks matter to your work, and use the listed comparison points to assess how each entry addresses them.
29 carbon accounting software ranked on what their makers publish — plans and prices, free tiers, platforms and the facts on their own pages.
4 of the 25 here have a free tier you can use, 0 have open-source code on record, and 0 have full bars: free, open, on most of your devices and documented.
| # | App | Signal | Free tier | Open code | Devices | From | Score |
|---|---|---|---|---|---|---|---|
| 1 | CarbonfactWeb · API | Two bars | — | 1 of 6 | Free | 6.4 | |
| 2 | CarbonToolWeb · API | Two bars | — | 1 of 6 | $166.67/mo | 6.4 | |
| 3 | GreenioWeb · API | Two bars | — | 1 of 6 | ₹2,999/mo | 6.4 | |
| 4 | PersefoniWeb · API | Two bars | — | 1 of 6 | Free | 6.4 | |
| 5 | CO2 AIWeb · API | One bar | — | — | 1 of 6 | — | 5.5 |
| 6 | CarbonInkWindows · Mac | No signal | — | — | 2 of 6 | — | 5.3 |
| 7 | 50X ImpactWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 8 | ACT Group Decarbonization PlatformWeb | One bar | — | — | 1 of 6 | — | 5.2 |
| 9 | ArborWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 10 | CarbonSmartWeb | One bar | — | — | 1 of 6 | — | 5.2 |
| 11 | Carbonstop CcloudWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 12 | EcoRekoWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 13 | Hedgehog Carbon PlatformWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 14 | NormativeWeb | One bar | — | — | 1 of 6 | — | 5.2 |
| 15 | Plan AWeb | One bar | — | — | 1 of 6 | — | 5.2 |
| 16 | scopedWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 17 | SINAI TechnologiesWeb | One bar | — | — | 1 of 6 | — | 5.2 |
| 18 | SweepWeb | One bar | — | — | 1 of 6 | — | 5.2 |
| 19 | VaayuWeb | No signal | — | — | 1 of 6 | — | 5.2 |
| 20 | WatershedWeb | One bar | — | — | 1 of 6 | — | 5.2 |
| 21 | BigMileWeb · API | One bar | — | — | 1 of 6 | — | 5.0 |
| 22 | CarbonAnalyticsWeb · API | One bar | — | — | 1 of 6 | £69.99/mo | 5.0 |
| 23 | CarbonChainWeb · API | One bar | — | — | 1 of 6 | — | 5.0 |
| 24 | Carbon Accounting AIWeb | No signal | — | — | 1 of 6 | — | 4.8 |
| 25 | ClimateTrackerWeb | No signal | — | — | 1 of 6 | — | 4.8 |
Is your app on this list?
Numbered spots on this list can be sponsored. They are labelled, and the editorial order and scores never change for payment.
Questions about this list
Which carbon accounting software is ranked first on Freedom251?
Carbonfact is ranked #1 of 29 with a score of 6.4. CarbonTool is second and Greenio third.
How many of these have a free plan?
4 of the 25 on this page publish a free plan on their own pricing pages.
Which is the cheapest paid option?
On this page, CarbonAnalytics has the lowest first paid tier we found: £69.99/mo.
How is this list ranked?
Ranked free-and-open first: a usable free tier and open-source code, then the platforms it runs on and its documentation. Paid placements never change a rank.