Slack sustainability score: 39/100
Slack is a cloud-based workplace messaging and collaboration platform founded in 2009 and headquartered in San Francisco. Acquired by Salesforce in July 2021, it serves millions of users globally.
More about Slack
As a SaaS business, Slack has minimal direct environmental impact but lacks independent sustainability disclosure and operates under its parent's consolidated reporting.
Founded 2009Head office San Francisco, USAStaff ~3,500Revenue ~$2.3BWebsite ↗
Slack has no independent sustainability reporting; all environmental data is buried in parent Salesforce's consolidated metrics. The company recently dropped absolute Scope 3 reduction targets in favor of intensity metrics—a hallmark greenwashing move. No Slack-specific emissions, waste, water, or nature data exists; renewable energy claims rest on market instruments, not additionality.
Slack scores 39/100 (Below expectations) on SINK's independent climate assessment, scored from public data only. Scores are free. Companies can never pay for anything about their own score. Last verified May 2026.
That places Slack joint 432nd of 934 companies scored, and joint 34th of 73 in SaaS / Digital Services.
What is Slack doing well, and where does it fall short?
Strongest on Energy Source and Carbon Footprint: Operations (6/10, 4/10). Weakest on Emissions Trajectory and Nature & Biodiversity Impact (3/10, 3/10).
Where Slack lost points
For each question that lost points, the evidence our public rubric looks for that we didn't find.
- Emissions from its own operations4/10No full Scope 1 and 2 figures worked out to the GHG Protocol.
- Emissions from its supply chain4/10Most of its supply-chain (Scope 3) emissions aren't measured.
- Whether its emissions are falling3/10No evidence its emissions are falling, not even from energy bills or mileage.
- How clean its energy is6/10Less than 90% of its energy shown to be renewable.
- Its effect on nature3/10No assessment of its effect on nature, and no basic environmental policy.
- How it uses materials and handles waste3/10No active waste reduction, reuse or repair shown.
- Its effect on water3/10No monitoring of water use, or no measures to reduce it.
- Its climate targets4/10Its targets aren't science-based or committed to the Science Based Targets initiative.
- How openly it reports4/10No dedicated sustainability role, board oversight or public report.
- Its record on controversies4/10Points deducted for controversies or its business model. The finding is under question 10.
A score changes when the evidence does. We use new published evidence at the next rescore. Anyone can send us new evidence, free. How to send it.
How is Slack's SINK score calculated?
Same ten questions for every company. No private weighting.
SINK = (0.3 × Base + 0.7 × Performance) × ScaleHas Slack's score changed?
Slack's score has moved from 37 to 39 across 2 recorded reviews, up 2 points.
- 37 → 39+229 October 2026
Correction: score 37 → 39; the published score did not follow from its own base, performance and size deduction (arithmetic error, corrected 29 October 2026).
- Scored 376 April 2026
Initial score at platform launch
What evidence is Slack's score based on?
10 sources used in this assessment. All publicly available. Each row shows which of the ten questions it informed.
50% of them were published by Slack itself; the rest come from independent sources.
Scored on 6 April 2026 under an earlier version of our method. We're re-checking it under the current method.
If you believe a source has been misread or a newer version exists, submit a challenge.
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How does Slack compare with other saas / digital services companies?
Where Slack sits among saas / digital services peers.
Among the 73 major saas / digital services brands we've scored, Slack is tied =34th of 73, with 2 others.
Who scores higher in SaaS / Digital Services?
The 3 companies in the sector scoring nearest above Slack.
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See the breakdown →Stripe publishes almost no corporate environmental data despite $5.1B revenue and 8,000 employees.
See the breakdown →Which companies moved this week, and why.
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