Case study · E-commerce extension
GreenCart — the climate contribution at the moment of payment
A Shopify extension that adds a “climate contribution” line to the payment page: the customer offsets the carbon footprint of their delivery in one gesture, the offset is purchased automatically and a certificate is emailed. Designed, published and operated by SeedVision.
Engagement period: · Page last reviewed on
Context
GreenCart Checkout is aimed at Shopify merchants who want to offer carbon-compensated delivery without weighing down their purchase flow. At payment time, the customer sees a climate contribution line computed from the delivery distance; if they leave it ticked, carbon credits are purchased automatically on settlement, funding a reforestation project in France, and a PDF certificate is emailed to them. The merchant tracks offsets, CO₂ compensated, certificates and billing from a dashboard.
Challenge
Everything happens at the most sensitive spot of a store: the payment page. A component inserted there has no right to fail — if it slows down or breaks settlement, it costs the merchant more than it will ever bring. The environmental promise also had to be verifiable: an offset with an opaque calculation and no proof looks like greenwashing, which is exactly what European law now regulates.
Approach
SeedVision built GreenCart as a Shopify checkout extension — the only supported path since theme-based checkout customisation was switched off — with one principle: the store never depends on us. The calculation is published (0.09 kg of CO₂e per kilometre travelled), the offset is triggered on settlement with no merchant action, and the proof goes to the customer as a certificate. The business model follows the same logic: free to install, a 12% commission on contributions, billed monthly through Stripe — the extension only earns when it serves.
Engagement timeline
- — Design and release. Building the checkout extension, the distance-based calculation engine, automatic carbon-credit purchase, the certificate and the merchant dashboard, then publishing.
- — Continuous operation. Watching the payment insertion point, tracking offsets and Stripe billing, maintaining the six served languages.
Before and after
Offsetting a delivery
Before: A separate step after purchase, which nobody takes
After: One line at payment time, one gesture
Credibility of the promise
Before: “Green delivery” with no figure and no proof
After: A published per-kilometre calculation and a certificate emailed to the customer
Cost for the merchant
Before: One more subscription, profitable or not
After: Free to install, commission only on actual contributions
Results
- A “climate contribution” line built into the Shopify payment page, ticked by default
- Published calculation: 0.09 kg of CO₂e per delivery kilometre
- Offset purchased automatically on settlement, funding a reforestation project in France
- PDF certificate emailed to the customer after purchase
- Merchant dashboard: offsets, CO₂ compensated, certificates, billing
- Six languages served: French, English, Spanish, German, Portuguese, Italian
- Free to install — 12% commission on contributions, billed through Stripe
Technologies and scope
- Extension Shopify
- Paiement
- Stripe
- Climat
- En production depuis 2025
Engagement period:
What the engagement covers, block by block
- Checkout extension — A contribution line inserted into the Shopify payment page, ticked by default, with no change to the store's theme.
- Offsetting and proof — Published per-kilometre calculation, automatic carbon-credit purchase on settlement, PDF certificate emailed to the customer.
- Dashboard and billing — Tracking of offsets, CO₂ compensated and certificates issued; monthly commission billing through Stripe.
What running it demands
- Payment must never depend on us — An incident on our component cannot be allowed to block a sale. The insertion point is treated as a no-failure zone: if the extension does not respond, payment carries on without it.
- Proof is part of the product — An offset without a certificate is an assertion. The certificate emailed to the customer and the merchant's dashboard are not comfort features: they are what makes the promise verifiable.
- Six languages, one mechanic — The text served to the customer adapts to their language, but the calculation, the offsetting and the billing stay identical everywhere — a single logic to operate and audit.
Architecture choices, and why
- An official extension rather than a theme modification — Since checkout.liquid was switched off on payment pages, the extension is the only path Shopify supports. It is also the safest: the isolation the platform enforces guarantees that a defect in the component cannot break settlement.
- A published calculation rather than a black box — 0.09 kg of CO₂e per kilometre, in plain sight. A contestable public figure beats an opaque algorithm: it is what lets an environmental claim stand up to European law and to a curious customer alike.
- Commission rather than subscription — Free to install, remunerated at 12% on contributions actually paid, billed monthly through Stripe. The alignment is mechanical: the extension only earns money when it is useful to the merchant and their customers.
Technical and regulatory milestones
Public, dated facts that constrain the scope.
- — Shopify switches off theme-based checkout customisation. A public platform milestone: on that date the legacy checkout customisation mechanism (checkout.liquid) was turned off on the information, shipping and payment pages. Cited here because it dictates the architecture: on Shopify's payment page, an official extension is the only supported path.
- — The EU directive against greenwashing enters into force. A public regulatory milestone: Directive (EU) 2024/825 on empowering consumers for the green transition regulates generic environmental claims. Cited here because it constrains how any offsetting product communicates — hence a published calculation and a delivered proof, rather than an unverifiable green promise.
Questions about this engagement
What happens if GreenCart fails during a payment?
Payment carries on without the contribution line. The insertion point is treated as a no-failure zone: the extension adds to the flow, it never stands in its way — and the isolation Shopify enforces on checkout extensions guarantees a component defect cannot break settlement.
How does the customer know their contribution actually served?
Through proof: the calculation is published (0.09 kg of CO₂e per delivery kilometre), carbon credits are purchased automatically on settlement, funding a reforestation project in France, and a PDF certificate is emailed after purchase. The merchant tracks offsets and certificates from the dashboard.
How much does GreenCart cost a Shopify merchant?
Installation is free and there is no subscription: GreenCart takes a 12% commission on the climate contributions paid by customers, billed monthly through Stripe. If nobody contributes, the extension costs nothing.
Related services
- MLOps industrialisation — 15 to 30 days
- Run & maintenance — Monthly retainer or daily-rate engagements
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- KizzyDance — 2018 → present
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Talk about your project
Facing a challenge close to GreenCart — write to contact@seedvision.fr — reply within 24 hours.