Carbon Credit Companies and Providers Compared: Models, Fees, and Retirement APIs
All entries verified September 1, 2026. Reviewed quarterly. Where a company does not publish a figure, this comparison says "not published" rather than estimating it.
The carbon credit companies and providers selling credits today fall into four broad groups: marketplaces with publicly listed prices (Carbonmark, ClimateTrade), exchanges built for institutional volume (Xpansiv's CBL, Carbon Trade Exchange), bank-distributed settlement networks (Carbonplace), and API-first providers that embed offsetting into software (Carbonmark, Cloverly, Patch). Carbonmark appears twice because its marketplace and its API are the same product.
Key takeaways
- Only two of the seven providers compared here publish figures you can read without a sales call. Carbon Trade Exchange publishes an account and trading fee schedule; Carbonmark publishes live per-tonne listing prices. The remaining platforms provide a quote on request after onboarding procedures have been completed.
- Minimum order size is the fastest disqualifier. Carbonmark retires from 0.001 tCO₂e (1 kg) for select credits where the underlying registry supports this functionality. CTX quotes retail volumes from 10 tCO₂e through its partner channels. Exchanges and bank networks do not publish a minimum at all.
- Four providers expose retirement through a published API: Carbonmark, Cloverly, Patch, and, since August 25, 2026, Carbon Trade Exchange. Only some of them return machine-readable proof of the retirement itself.
- The institutional end of the market is consolidating. Climate Impact X and Carbonplace announced on August 26, 2026 that they intend to merge, subject to Monetary Authority of Singapore approval, with integration expected in the first quarter of 2027.
Carbon credit companies and providers compared
One row per provider. "Not published" means the company does not disclose the figure publicly: a legitimate commercial choice, and not evidence of anything worse.
| Provider | Model | Minimum order | Pricing transparency | Published fees | Best for |
|---|---|---|---|---|---|
| Carbonmark | Marketplace, API-native | 0.001 tCO₂e (1 kg) on supported credits | Live per-tonne listing prices, public | No seller-side listing fees. A variable buyer-side fee applies | Small to mid volumes where public proof of retirement matters |
| Xpansiv / CBL | Spot exchange, central limit order book | Not published | Order book visible to qualified participants; benchmark contracts (GEO, N-GEO, C-GEO) | Not published. A platform access fee was introduced in January 2024, waived above minimum trading volumes | Institutional volume and benchmark price exposure |
| Carbon Trade Exchange (CTX) | Spot exchange plus buyer-only accounts | 10 tCO₂e for retail buyers via the partner channel | Sellers set their own listed prices; wholesale credits quoted at $0.25 to $65 per tonne (August 2026) | Yes. Standard account setup $650, buyer-only account $50 one-time with a 10% trading fee, referred OTC trades 0.5% buyer and 1.5% seller | Buyers who want a fee schedule they can read before signing up |
| Carbonplace | Bank-distributed settlement and portfolio platform | Not published | Not published | Not published | Corporates already transacting through a member bank |
| Cloverly | API-first provider with managed inventory | Not published. Supports both bulk and micro transactions; focus is shifting toward a supplier-focused credit management platform | Real-time project pricing through the API; not published on the website | Not published | Product teams that want inventory and retirement managed for them |
| Patch | Procurement platform and API, advisory-led | Not published. Orders can be placed by tonnage or by total price | Not published | Not published | Buyers running an RFP with strategist support |
| ClimateTrade | Marketplace plus checkout API and widget | Not published | Not published | Not published | Adding offsetting to an e-commerce checkout |
Coverage, retirement, and settlement
Retirement is the act of permanently cancelling a credit in the registry that issued it, so it can never be resold or claimed again. It is the step that turns a purchase into an emissions claim, which is why how each provider evidences it matters as much as how it sells.
| Provider | Registries covered | Project types | Retirement proof | API | Settlement |
|---|---|---|---|---|---|
| Carbonmark | Verra, Puro.earth, ICR, Cercarbono | Forestry, renewables, cookstoves, biochar, blue carbon across 20+ countries. Live project count varies with developer listings | Self-serve. Public certificate at app.carbonmark.com/retirements/{address}/{number}, with an onchain transaction hash and public blockchain transaction link | Yes, retirement exposed. v20 is the latest stable release, live since August 17, 2026 | Card, bank transfer, or onchain USDC. Retirement is instant |
| Xpansiv / CBL | Verra, Climate Action Reserve, and others through the integrated registry network | Standardized benchmark contracts plus project-specific credits | Through the participant's own registry account | A developer portal covers Xpansiv products; retirement exposure not published | T+0 same-day settlement of CBL-matched trades |
| Carbon Trade Exchange (CTX) | UN CDM and Gold Standard per the trading FAQ; Global Carbon Registry and BioCarbon Standard per the fee schedule | Registry-native credits, seller-listed | "Buy to retire only" on the partner channel, with certificates issued in the partner's name | Yes. Exchange API launched August 25, 2026: live listings feed, fee calculator, programmatic trading | Card for buyer-only accounts; registry transfer otherwise |
| Carbonplace | 14: Verra, Gold Standard, Puro, ACR, CAR, Isometric, Cercarbono, BioCarbon, CSI, ART TREES, ICR, GCC, Rainbow, eva | Multi-registry portfolio holdings | Retire holdings across registries from a single account | Not published | Bank-style delivery versus payment, with no pre-payment or pre-posting of credits |
| Cloverly | Not published | Biochar, direct air capture, ODS destruction, improved forest management, afforestation, avoided deforestation, enhanced rock weathering, improved agricultural land management | Digital certificate per purchase, whole tonnes only. The registry certificate follows separately rather than instantly; inventory and retirement management in the dashboard | Yes, REST, with a sandbox environment and SOC 2 compliance | Not published |
| Patch | Not published. Covers carbon, SAFc, and RECs | Avoidance through removal, nature-based through engineered | Public order page that tracks an order from purchase to placement to retirement | Yes. Test keys prefixed key_test_, an OpenAPI 3 spec, and SDKs for Node, Python, and Ruby | Not published |
| ClimateTrade | Not published. 60+ certified projects | Mixed portfolio | Certificates available; however, it is unclear what minimum transaction size and micro-retirement support they offer | Yes, for footprint calculation and checkout offsetting | Multiple payment methods |
A note on AlliedOffsets. AlliedOffsets is a carbon market data provider and a Carbonmark integration partner, not a carbon offset seller, so it does not appear in the comparison above.
How this comparison was verified
Every entry comes from one of two places: the company's own public pages, developer documentation, or published fee schedule, read on the date noted at the top; or the Carbonmark competitive review, drawn from direct conversations with providers and listed in Sources below. There are no estimates in either table, and the cells that look empty are the finding rather than a gap in the research. Over time the data in the comparison tables above may become stale, which is why they carry a date and a quarterly review.
Broker, marketplace, or exchange: the short version
There are three primary models utilized for commercial activity in the carbon market:
- A broker sources credits on your behalf, negotiates with sellers, and earns a spread or a commission. Useful for large bespoke portfolios. Minimums are typically high and pricing is quoted rather than listed. A large number of intermediaries means more financing is directed to third parties rather than the carbon project developers themselves.
- A marketplace lists inventory at published prices and lets you transact yourself. Lower minimums, faster, and you see the price before you talk to anyone. Some marketplaces, like Carbonmark's, enable instant settlement through innovative payment infrastructure such as stablecoins on public blockchains.
- An exchange matches standardized contracts through an order book, with membership, onboarding, and institutional settlement. These exchanges are usually private, require onboarding, and are primarily utilized by large corporates.
That is the whole definitional budget here. For the full treatment of which model suits your business, read brokers versus carbon credit marketplaces in the VCM. This article answers the next question: which provider, and on what terms.
How to choose: five key questions
Whether you are an individual, a small to medium enterprise (SME), or a large corporate, there are a few key questions you can ask to guide your procurement strategy and who you partner with. We've outlined them below:
1. What is the minimum order? This eliminates more vendors than pricing does. For example, if you need 40 tonnes and the exchange only offers credits above hundreds of tonnes after a costly account onboarding process, the rest of the evaluation becomes academic.
2. Is the price published before I make contact? A listed price you can check is a different commercial relationship from a quote you have to request. If you have to defend the purchase internally, a public price is far easier to put in a memo than a negotiated one.
3. Can I see the retirement certificate, and can anyone else? Ask whether the certificate is public, whether it names your organization as beneficiary, and whether the record ties back to the registry of origin. This is the question most often answered vaguely.
4. Which registries does the provider actually reach? Registry coverage decides which methodologies and project types you can buy. Many platforms work with only a subset of the recognized carbon registries operating today, so if you have a specific project type in mind, coverage becomes a real constraint.
5. Can it be automated? If offsetting has to happen per transaction, per shipment, or per product, a portal or marketplace is not enough. You need an API, and specifically one that exposes retirements rather than purchases alone.
For technical buyers: comparing retirement APIs
The gap between "has an API" and "exposes retirement through the API" is where most integrations stall. Buying a credit programmatically is straightforward. Retiring one, and getting back proof you can hand to an auditor, is the part that varies.
| Provider | Auth and sandbox | Retirement exposed via API | Proof returned | Batch or bulk | Callbacks |
|---|---|---|---|---|---|
| Carbonmark | Bearer-token API key from developers.carbonmark.com. Free sandbox keys; production access after onboarding | Yes. POST /quotes, then POST /orders, polled on GET /orders until status is COMPLETED | Onchain transaction hash, and a public certificate URL | Orders are placed individually | Poll GET /orders. For agentic transactions, a separate x402 endpoint is supported |
| Cloverly | API key, with a sandbox environment | Yes. Estimates can be promoted to purchases, which reserve and retire credits | Digital certificate per purchase for whole tonnes | Documented for both bulk and micro transactions | Not published |
| Patch | API key, with distinct test keys (key_test_) | Orders are created and then placed; retirement status is tracked through the order lifecycle | Public order page showing status from purchase to placement to retirement | Not published | Not published |
| ClimateTrade | Developer portal registration; access costs not published | Offsetting through the API and the checkout widget | Certificate with a blockchain link. Micro-retirement support, and which standards allow it, are not published | Not published | Not published |
| Carbon Trade Exchange | API key, issued in minutes to approved partners | Yes. "Buy to retire only", with certificates in the partner's name | Retirement certificate in the partner's name | Not published | Not published |
Two points matter for anyone building on these. Fractional retirement changes what you can build: Carbonmark retires from 0.001 tCO₂e, which is what makes per-transaction, per-shipment, and round-up features viable without rounding every user's footprint up to a whole tonne. Scalability and auditability depend on the underlying infrastructure: Carbonmark's v20 release, live since August 17, 2026, extended listings, quotes, orders, and wallets across both the Polygon and Base blockchains, enhancing scalability and micro-retirement potential.
The full endpoint reference is at docs.carbonmark.com, and the integration overview at Carbonmark API and integrations.
Where Carbonmark fits
Carbonmark's own marketplace runs on its API. It's designed to be scalable and highly flexible for different software applications and industries.
What the comparison makes visible:
- Prices are listed, not quoted. You can see the per-tonne price of every project before you create an account.
- Minimum order size enables novel use cases. Retirement starts at 1 kg of CO₂e, which no exchange or bank network in this comparison offers.
- Retirement is self-serve and the certificate is public. Every completed retirement returns an onchain transaction hash and a certificate URL that anyone can open, as well as carbon provenance showing its trading history and registry issuance information. This is helpful for companies requiring deep auditing for their environmental claims.
- The API exposes retirement, not just purchase, with free sandbox keys and no pre-purchased inventory required.
Whether you're an SME seeking an immediate purchase and retirement of credits, or a software company specializing in carbon compensation, you can easily compare live projects and prices or talk to the Solutions team if you require a bespoke solution.
Frequently asked questions
Which companies sell carbon credits?
Carbon credits are sold by marketplaces (Carbonmark, ClimateTrade), exchanges (Xpansiv's CBL, Carbon Trade Exchange), bank-distributed settlement networks (Carbonplace), and API-first providers (Carbonmark, Cloverly, Patch). Brokers also sell credits, sourcing them on a buyer's behalf for a commission or spread rather than listing inventory publicly.
What is a carbon credit broker?
A carbon credit broker is an intermediary that sources carbon credits on a buyer's behalf, negotiates terms with sellers, and earns a commission or a spread on the transaction. Brokers typically quote prices on request rather than listing them, and often set minimum order sizes in the hundreds or thousands of tonnes.
What is the difference between a carbon credit broker and a marketplace?
A broker transacts on your behalf and quotes you a price. A marketplace lists inventory at published prices and lets you transact yourself. Brokers suit large bespoke portfolios and add advisory value; marketplaces suit smaller volumes, faster timelines, and buyers who want to see the price before making contact. Going the broker route generally exposes a buyer to additional intermediaries.
What is the minimum order for carbon credits?
It depends entirely on the provider. Carbonmark retires from 0.001 tCO₂e (1 kg) for fully tokenized credits, on the select registries that support this functionality. Carbon Trade Exchange quotes retail volumes from 10 tCO₂e through its partner channel. Exchanges and bank-distributed networks generally do not publish a minimum, and brokers commonly start in the hundreds or thousands of tonnes.
Which carbon credit platforms have an API?
As of September 2026, Carbonmark, Cloverly, Patch, and ClimateTrade all publish APIs, and Carbon Trade Exchange launched an Exchange API on August 25, 2026. Carbonmark, Cloverly, Patch, and Carbon Trade Exchange expose retirement through the API rather than purchase alone. ClimateTrade's API covers footprint calculation and checkout offsetting.
How do I verify a carbon credit retirement?
Ask for the retirement record itself, not a summary of it. On Carbonmark, every completed retirement returns an onchain transaction hash, a blockchain-secured transaction link, and a public certificate URL naming the beneficiary, project, and tonnage, all of which a third party can open and check independently.
Do carbon credit providers publish their fees?
Mostly no. Of the seven providers compared here, Carbon Trade Exchange publishes an account and trading fee schedule, and Carbonmark publishes live per-tonne listing prices. The rest quote on request. As of August 2026, the majority of market activity is still transacted on an over-the-counter (OTC) basis, which makes internal cost comparison harder for buyers.
Related reading
- Brokers versus carbon credit marketplaces in the VCM, for choosing between the models rather than the players.
- Understanding carbon credit pricing, for why the same tonne trades from under a dollar to several hundred.
- How to buy carbon offsets, for the step-by-step purchase and retirement process.
- Carbonmark API and integrations, for the developer path.
Sources
All sources accessed September 1, 2026.
- Carbonmark developer documentation, including the v20 latest stable release notes (live August 17, 2026), quickstart, retire-carbon, and checkout service pages: https://docs.carbonmark.com/
- Carbonmark, Buy Carbon Credits: https://www.carbonmark.com/buy-carbon-credits
- Carbonmark, API and Integrations: https://www.carbonmark.com/api-and-integrations
- Xpansiv, CBL trading platform and carbon commodities pages: https://www.xpansiv.com/trading-platforms/cbl
- Carbon Pulse reporting on the CBL access fee introduced in January 2024: https://carbon-pulse.com/243651/
- Carbon Trade Exchange fee updates, effective April 1, 2026: https://ctxglobal.com/carbon-trade-exchange-ctx-enters-high-growth-phase/
- Carbon Trade Exchange trading FAQs: https://ctxglobal.com/trading-faqs/
- Global Environmental Markets, CTX Exchange API launch, August 25, 2026: https://www.gemglobal.com/carbon-trade-exchange-launches-exchange-api-solution-opening-direct-access-to-the-global-carbon-credit-marketplace/
- Carbonplace, How It Works (14 registries listed): https://carbonplace.com/how-it-works
- Climate Impact X and Carbonplace merger announcement, August 26, 2026: https://climateimpactx.com/press-release/climate-impact-x-and-carbonplace-combine-to-build-infrastructure-for-next-phase-of-environmental-markets/
- Cloverly, API and Buyers pages: https://cloverly.com/api
- Patch, How It Works, and the Patch Node client library documenting test keys and order operations: https://www.patch.io/how-it-works
- ClimateTrade developer portal: https://developers.climatetrade.com/
- Carbonmark competitive review, September 2026: direct conversations with providers, the basis for the Cloverly certificate-timing and whole-tonne entries and the ClimateTrade access-cost and micro-retirement entries.
