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Exchange API Solution
Executive Summary & Capability Overview
1. Executive Overview
CTX – Carbon Trade Exchange has launched a dedicated Exchange API Solution that allows external organisations to connect directly to the CTX carbon credit marketplace from their own systems, websites, or applications.
What this means in plain terms: any company or developer who holds an authorised API key can now retrieve live carbon credit listings, calculate exact purchase costs, and execute trades — all programmatically, without ever logging into the CTX website. CTX becomes a trading engine that partners can embed inside their own products.
This is a significant commercial milestone. It opens CTX to a new category of partners — platforms, storefronts, brokers, and enterprise buyers — that could not previously integrate with the exchange in an automated way. Each integration partner is a potential growth channel that brings additional trade volume to CTX.
2. What the API Enables
The API gives authorised partners three core capabilities, delivered through simple, secure web calls:
Live Listings Feed
A real-time snapshot of all available sell-side carbon credit offers on the exchange: project details, vintage, standard (e.g. VERRA, Gold Standard), quantity, price, and whether the price is negotiable.
Partners can display CTX inventory inside their own platforms, driving awareness and demand without requiring buyers to visit CTX directly.
Fee & Cost Calculator
Given a specific listing and volume, the API returns an exact cost breakdown (unit price, CTX transaction fee, registry fee, total) in both the traded currency and the buyer’s invoice currency — matching what the buyer would see on the CTX checkout screen.
Removes price ambiguity from partner integrations; buyers see the full cost before committing, increasing conversion rates and reducing disputes.
Programmatic Trading
Partners can execute a real purchase against a live listing via a single API call. The trade is processed end-to-end on the CTX platform: funds move, inventory is updated, and settlement is triggered, exactly as if the buyer clicked “Buy” on the CTX website.
Enables automated, high-frequency purchasing workflows (e.g. a corporate buyer retiring credits monthly, or a storefront offsetting customer orders at checkout). Every trade cleared this way is a CTX transaction.
3. Key Platform Features
3.1 SECURE API KEY ACCESS MANAGEMENT
Every API partner is issued a unique secret key by the CTX administrator team through a dedicated management console (BusinessAdmin → API Services). There are no shared or public keys; access is individual, traceable, and revocable at any time.
- Keys can be created, revealed, rotated (invalidate old, issue new), or disabled at any moment.
- Each key is cryptographically protected in the CTX database; only the authorised administrator or the partner themselves can view it — and only after passing multi-factor verification.
- Partners can also manage their own key on the CTX Member API page, including requesting their secret via a one-time code sent by email or SMS.
3.2 FULL USAGE TRANSPARENCY
- CTX has built-in usage analytics for every API client. The dashboard shows calls made today, this month, and in total, broken down by endpoint (Listings, Fees, Buy) and by the source of the call (browser website, back-end server, or specific IP).
- Administrators can set rate, daily, and monthly usage limits per client to prevent abuse or runaway usage.
- Usage data is the foundation for future commercial conversations around tiered access plans or usage-based pricing.
3.3 BROWSER & WEBSITE INTEGRATION (CORS)
Partners who want to call the API directly from a website (browser-side JavaScript) can register their approved web addresses (origins) with CTX. The exchange then grants secure cross-origin access only to those registered addresses and only while their API access is active.
This means a retail e-commerce site, a corporate sustainability dashboard, or any web application can query live CTX listings and even execute purchases directly from the browser — without needing a separate back-end server.
3.4 LISTING VISIBILITY CONTROLS
CTX administrators can configure visibility rules that hide specific listings from individual partners or from all API clients globally. Rules can filter by:
- Vintage range (e.g. show only 2018–2024 credits)
- Carbon standard (allow-list: e.g. only VERRA and Gold Standard)
- Project type, region, or country (block-list)
This gives CTX precise commercial control over what each partner sees — enabling differentiated product tiers, geographic restrictions, or client-specific catalogues. Importantly, the same rules also apply to the CTX website view for API-enabled accounts, keeping both channels perfectly consistent.
3.5 SELF-SERVICE PARTNER ONBOARDING
Partners can register their own browser origins, view their usage statistics, and retrieve their API key through the CTX Member API page.
4. Integration Process (Architecture)
How a partner’s website connects through to CTX via the API — from onboarding and key issuance through to a completed, settled trade.
Retail website → CTX API → Fees Engine / CTX core → Retail Payment Gateway → transaction approved and settled.
5. Who Can Use the CTX Exchange API
The API is designed to serve three categories of integration partner:
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Corporate Buyers & ESG Platforms
Large organisations with sustainability commitments that want to automate their carbon credit purchasing — for example, automatically retiring credits each quarter against a net-zero target — without manual intervention on the CTX website. The API also allows them to embed a live CTX catalogue into their internal sustainability dashboards.
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Retail & E-Commerce Storefronts
Online retailers and booking platforms that want to offer carbon offset add-ons at the point of sale. With the API, they can show a live selection of credits, calculate the exact cost (including fees) and complete the purchase in a single checkout flow — fully branded under their own experience.
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Brokers & Data Vendors
Intermediaries and market-data providers that need access to live CTX offer data to quote prices to their own clients, build price history charts, or publish carbon market indices. The API delivers a structured, filterable data feed in real time.
6. Security & Compliance Summary
Individual secret keys
Every partner is issued their own unique key. No shared keys exist anywhere in the system.
Encrypted key storage
Keys are stored AES-encrypted in the CTX database. Even the CTX team cannot see a key in plain text without going through the secure reveal process.
Multi-factor key reveal
To view their API key, members must pass a one-time code sent by email or SMS (Azure Communication Services).
Instant revocation
Any key can be disabled or rotated by the CTX administrator or the partner themselves in seconds. A rotated key is immediately invalidated.
Per-key buyer binding
The Buy endpoint links each API key to exactly one buyer account. A key cannot purchase on behalf of a different account, preventing identity spoofing.
Browser origin control (CORS)
Browser-based calls are only permitted from web addresses the partner has explicitly pre-registered with CTX. Disabled clients receive no browser access.
All traffic over HTTPS
All API communication is encrypted in transit. No plain-text credentials are ever transmitted.
Usage limits & monitoring
Administrators can set rate, daily, and monthly call limits per client. All usage is logged and visible in real time.
7. Commercial Highlights
New revenue and volume channel
Every trade executed through the API generates the same CTX transaction fee as a website trade. Partners who bring volume via the API increase CTX’s total traded volume with no additional website infrastructure cost.
Differentiated product offering
The Listing Visibility feature allows CTX to offer curated, partner-specific carbon credit catalogues — a potential foundation for premium access tiers or white-label partnerships.
Usage data for commercial conversations
CTX now has call-level data for every API partner — what they access, how often, and from where. This data supports evidence-based conversations about value delivered and pricing tiers.
Low onboarding friction
A partner can be issued an API key in minutes via the BusinessAdmin console. Self-service key management and usage visibility reduce ongoing support overhead.
Fully live and deployed
The API is operational in production. The core three endpoints (Listings, Fees, Buy) have been end-to-end verified with a live retail integration partner. Real trades have cleared through the API.
8. Frequently Asked Questions.
1. How we can apply for a Corporate API Account and receive API access?
Through the application page https://login.ctxglobal.net/ Create an account and choose Corporate API from the dropdown menu. You must use a different email address than that already associated with an existing CTX account.
2. What are the commercial conditions, including setup, monthly or transaction fees?
There is a US$5,000 account opening fee and a US$1,000 account deposit required to activate trading. A 10% fee applies to each transaction made through the CTX platform and is added to the listing price. There are no monthly fees.
3. How do wholesale pricing and partner markup work?
The CTX API member buys from the CTX platform at the wholesale value. You can amend the prices on your own website where your clients purchase credits. The Viking Carbon test API website shows an example where US$5.00 has been added per credit.
4. How are payments handled?
nce the US$5,000 opening fee is paid and the US$1,000 deposit is made, CTX extends a US$5,000 line of credit to the API account. This allows end customers to complete purchases through your website even when the account balance is low. Credit retirement and certificate issuance are processed once sufficient funds are available. You have 48 hours to cover any shortfall.
5. What does “Line of Credit” mean in CTX terms?
It is a pre-approved spending buffer that allows customer transactions to appear complete in real time without interrupting their experience. It is not a borrowing facility: no interest is charged and no debt is created. It acts as a short-term bridge until funds are settled in your CTX account.
6. How does the Buy-to-Retire process work in practice?
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7. In whose name are retirement certificates issued?
The certificate is always issued in the name of the CTX API Account holder.
8. What KYC, AML or regulatory requirements apply?
The same KYC and AML documents required for a standard account apply. If you are already a CTX member, existing documents can be used if they are current. Documents are considered current when issued within the last 12 months. Please confirm with the CTX team if unsure.
9. Is a sandbox or test environment available?
A test environment is available for demonstrations. Once your account is approved, you can be granted a replica account in UAT as a sandbox environment.
10. When are technical documentation, API specifications and authentication requirements provided?
These are provided once the account has been opened.
11. What is the expected onboarding process and timeline?
Once the application is processed, payment is received and KYC/AML documents are provided, the account can be live immediately.
