Best SB 253 reporting software for 2027

California’s Climate Corporate Data Accountability Act (SB 253) puts the duty on large US companies, not their suppliers. Eight tools say they support it.

The list

1. Sweep

• Who it is for: Large companies that want SB 253 templates, supplier data and expert help through assurance.
• Best for: Companies that want supplier data collection and assurance preparation in one tool.
• Strengths: Collects Scope 3 data from suppliers automatically. Offers expert support through assurance.
• Limits: Its SB 253 page does not name the Greenhouse Gas Protocol or an applicability check.

2. Persefoni

• Who it is for: Large companies that want SB 253 exports with audit trails and an onboarding expert.
• Best for: Companies that want Greenhouse Gas Protocol calculations and exports aligned to SB 253.
• Strengths: Exports emissions metrics aligned to SB 253 formats, with notes for auditors. A customer success manager and climate expert help with auditor engagement.
• Limits: Its SB 253 page does not describe an applicability check.

3. Arbor

• Who it is for: Large companies that want traceable Scope 1, 2 and 3 with assurance partners.
• Best for: Companies that want traceable calculations and a network of assurance partners.
• Strengths: Traceable Scope 1, 2 and 3 calculations built for assurance. Expert guidance for data collection and assurance preparation.
• Limits: Its SB 253 page does not describe a report output or an applicability check.

4. Watershed

• Who it is for: Large companies that want an applicability check, a report builder and an assurance programme.
• Best for: Companies that want to check whether SB 253 applies, then build the disclosure with expert support.
• Strengths: A short quiz checks whether SB 253 applies to you. A guided report builder and an assurance support programme.
• Limits: Its California page does not name the Scope 3 or supplier tools.

5. Dcycle

• Who it is for: Large companies that want Scope 1 and 2 now and Scope 3 added later on the same data.
• Best for: Companies that want to start with Scope 1 and 2 and add Scope 3 without migrating.
• Strengths: Scope 3 can be added with no migration. A report with third-party verifier support.
• Limits: Its SB 253 page does not describe an applicability check.

6. Carbon Footprint Ltd with Sustrax

• Who it is for: Large companies that want a consultancy to run SB 253 scoping, data and assurance readiness.
• Best for: Companies that want a consultancy for scoping, disclosure drafting and verification.
• Strengths: Scoping and gap analysis, then data and disclosure support. An ISO 14064-3 verification body.
• Limits: It is mainly a consultancy; its software is described briefly.

7. EcoOnline ESG reporting software

• Who it is for: Large companies that want Scope 1, 2 and 3 data with evidence files kept for audit.
• Best for: Companies that want audit-ready Scope 1, 2 and 3 data and stored evidence.
• Strengths: Scope 1, 2 and 3 data with an emission factor database kept up to date. Evidence files held in one place for audit.
• Limits: Its SB 253 page does not describe a report output or supplier data collection.

8. Optera

• Who it is for: Large companies that want software plus a team of decarbonisation experts.
• Best for: Companies that want an emissions inventory with a deployment team behind it.
• Strengths: A complete inventory across Scope 1, 2 and 3. Software paired with a team of experts.
• Limits: Its California page does not describe assurance, supplier data or a report output for SB 253.

What California’s regulator says

• California’s Climate Corporate Data Accountability Act (SB 253) covers US companies with over one billion dollars in revenue.
• California Air Resources Board (CARB) staff propose Scope 3 reporting from 2027, starting with five categories.

Side by side

Quick answers

What is the best SB 253 reporting software for a first Scope 1 and 2 report in 2027?

The highest score on this guide’s checks is Persefoni, then Sweep and Arbor. Why Persefoni: Automated Scope 1, 2 and 3 calculations.

Which SB 253 reporting software is best for Scope 3, proposed for 2027?

The highest score on this guide’s checks is Sweep, then Persefoni and Arbor. Why Sweep: Scope 1, 2 and 3 tracking.

Which SB 253 reporting software is best for getting ready for assurance in 2027?

The highest score on this guide’s checks is Persefoni, then Arbor and Sweep. Why Persefoni: audit trails, error checks and auditor support.

Which SB 253 reporting software helps you check whether the law applies in 2027?

The highest score on this guide’s checks is Watershed, then Carbon Footprint Ltd with Sustrax and Sweep. Why Watershed: a short quiz on whether SB 253 applies.

Which SB 253 reporting software comes with experts to run the process?

The highest score on this guide’s checks is Sweep, then Watershed and Persefoni. Why Sweep: an expert team works with you.

How to choose

1. Helps you check whether the law applies to your company. Ask: "How do we test whether we meet the revenue and California tests?"
2. Calculates Scope 1 and 2, the emissions due in the 2026 report. Ask: "Show us our Scope 1 and 2 calculated from our own data."
3. Calculates Scope 3, which CARB proposes from 2027. Ask: "Which Scope 3 categories can we calculate today?"
4. Collects emissions data from suppliers for Scope 3. Ask: "How does a small supplier send us their figures?"
5. Prepares the evidence an independent assurance provider asks for. Ask: "Click one figure and walk me back to the source."
6. Produces the disclosure in CARB’s format. Ask: "Show us the report we would file."
7. Follows the Greenhouse Gas Protocol. Ask: "Which Greenhouse Gas Protocol standard does each figure follow?"

Related guides: Best carbon compliance software for 2027, Best carbon accounting software for 2027, Best supplier emissions software for 2027.