Best CO2.js Alternatives ranked by AI · updated Aug 2026

CO2.js is an open-source JavaScript library for estimating the environmental impact of digital products and accessing sustainable web data. It is aimed at web developers and researchers who want calculation utilities they can run and adapt in their own applications.

Developer: The Green Web Foundation Price: Free and open source 🎯 thegreenwebfoundation.org

🔓 Open Source Carbon Accounting emissions api web sustainability

Top 6 CO2.js alternatives

Carbon Interface

Carbon Interface is an emissions-estimation API for developers building carbon calculators into apps, websites, and business workflows. It estimates emissions from activities...

Pros

Simple REST API designed for rapid integration
Covers common travel, energy, transportation, shipping, and food calculations
More accessible to small development teams than enterprise carbon-accounting platforms

Cons

Less comprehensive emissions-factor customization than Climatiq
Limited accounting, reporting, and supplier-management features
Coverage and methodology transparency may not satisfy complex enterprise inventories

Free for limited usage; paid plans available

Alternatives to Carbon Interface → Visit site

Watershed

Watershed is an enterprise carbon management platform for measuring emissions, setting reduction targets, and producing climate disclosures. It is aimed at companies...

Pros

Stronger enterprise data integrations than Carbonze
Broader support for climate targets, reporting, and supplier emissions
Well suited to large organizations with dedicated sustainability teams

Cons

More expensive and complex than Carbonze for smaller businesses
Requires substantial data preparation and implementation work
Not designed as a lightweight self-service calculator

Custom pricing

Alternatives to Watershed → Visit site

Normative

Normative is a business carbon accounting platform that helps organizations calculate emissions, identify hotspots, and plan reductions. It is built for companies...

Pros

Strong focus on detailed, auditable carbon accounting
Useful Scope 3 workflows for complex supply chains
Provides more structured reduction analysis than Carbonze

Cons

Typically requires more setup and data than a smaller platform
Pricing is not transparent for self-service buyers
May be more process-heavy for companies with simple inventories

Custom pricing

Alternatives to Normative → Visit site

Greenly

Greenly is a carbon accounting platform for businesses that calculates emissions, supports reduction planning, and provides sustainability reporting tools. It is particularly...

Pros

Generally more approachable for smaller businesses than enterprise platforms
Provides guided carbon assessment and reduction recommendations
Offers broader support for employee and supplier engagement than Carbonze

Cons

Advanced enterprise controls may be less extensive than Watershed or Plan A
Pricing and included capabilities vary by company size and plan
Automated estimates still need review when accurate primary data is available

Custom pricing

Alternatives to Greenly → Visit site

Climatiq

Climatiq Technologies GmbH

Climatiq provides an emissions-intelligence API and platform for developers, sustainability teams, and enterprises. Its standout capability is a large, traceable emissions-factor database...

Pros

Broader and more configurable emissions-factor coverage than Carbon Interface
Includes factor metadata, sources, regions, and audit-oriented provenance
Supports spend-based, activity-based, and supply-chain calculations

Cons

More complex to configure than Carbon Interface
Can be expensive for high-volume or enterprise usage
Requires more emissions-accounting knowledge for accurate modeling

Free tier; paid usage-based plans

Alternatives to Climatiq → Visit site

Electricity Maps

Electricity Maps provides APIs and datasets for real-time and historical electricity carbon intensity, aimed at software developers, energy analysts, and grid-aware businesses....

Pros

More detailed real-time and historical grid-intensity data than Carbon Interface
Useful for location- and time-aware electricity calculations
Provides map, API, and dataset access for software integrations

Cons

Primarily covers electricity carbon intensity rather than broad activity emissions
Does not replace a full travel, shipping, food, or corporate accounting API
Historical and commercial access may require a paid plan

Free options for limited use; paid plans available

Alternatives to Electricity Maps → Visit site

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