About SINK

A carbon sink absorbs more
than it emits.

Forests do it. Oceans do it. No major company does it yet.

SINK — the Sustainability Index for Networked Knowledge — scores every company 0–100 using the same open formula. One rubric. Public data. Community verified. No company can pay to change their score.

We're building the world's largest open database of real sustainability scores. Every score is sourced. Every score can be challenged. Every score is transparent.

Because the planet doesn't grade on a curve.

The acronym

What SINK stands for.

SSustainability

What we measure. Real environmental footprint — emissions, energy, supply chain, governance.

IIndex

How we measure it. One formula, scored 0–100, applied equally to every company on Earth.

NNetworked

Community verified. Open to challenge. Every score can be disputed with evidence. Transparency by design.

KKnowledge

Data-driven. Every score backed by sources. No opinions, no vibes — just evidence.

How we operate

Four principles, no exceptions.

Same rubric for everyone

A 10-person lighting company is scored using the same 10 questions as a $400B tech giant. The formula adjusts for industry and scale — the standards don't.

Public methodology

Every step of how we calculate a score is public. The formula, the rubric, the sources, the editorial reasoning. You can reproduce our scores from public data using our published methodology. No private weighting, no hidden logic, no proprietary tricks.

Open to challenge

Every question on every score can be challenged by anyone with evidence. Challenges are reviewed and published. We'd rather be corrected than wrong.

We grade against the planet

Scores above 75 are exceptionally rare. We don't inflate grades to make companies feel good. A score of 60+ is genuine leadership — the kind backed by verified data, science-based targets, and transparent governance.

The contrast

How SINK is different.

SINK
  • Funded by readers and institutions that license our data — never by the companies we rate
  • Public methodology — anyone can reproduce our scores
  • Community verification and open challenges
  • Free to search and share
Traditional ESG ratings
  • Funded by the companies being rated (conflict of interest)
  • Proprietary methodology — 'trust us'
  • Closed process, no public scrutiny
  • Paywalled behind enterprise contracts
Why this exists

The companies with the largest footprints pay to be rated.

The agencies use secret methodologies. The results are paywalled behind enterprise contracts that cost tens of thousands of pounds per year.

The result? ExxonMobil can receive an “A” rating from one agency and a “below average” from another — for the same year of operations. Consumers, journalists, and small investors have no way to know what's real.

SINK is the alternative: one formula, public data, open methodology. The same rules for a two-person startup as for a multi-billion-dollar tech giant — because transparency shouldn't scale with power.

The disclosure gap

Why some companies score lower than they should.

A small organic farm doing real work usually scores lower than a corporate brand that's just good at publishing reports. We think that's backwards.

SINK rates 500+ companies on the same 10 questions. We start with what's publicly known. Companies who've done work we couldn't find can submit it directly — energy bills, supplier audits, certifications. Same scoring rules apply. Paying gets your actual practice represented; it doesn't get you a better score for free.

Who we are

A small, independent team in the UK.

We are not funded by, affiliated with, or influenced by any company in our database. No investor, sponsor, or rated company has any say in how scores are calculated.

We believe sustainability data should be free, transparent, and open to scrutiny — not locked behind enterprise paywalls or controlled by the companies being rated.

If you want to get in touch, challenge a score, or suggest a company to add, email us at hello@sinkproject.com.

Help build the database

Independent scores aren't free.

Search the leaderboard. Challenge a score. Or back the project so it stays independent.