QA Engineer - APIs & SDKs (Contract - US, LATAM, Spain)

QA Engineer - APIs & SDKs (Contract - US, LATAM, Spain)

If you are interested, please apply here.

About Crossmint

Stablecoins and blockchains are upgrading the world's financial system — and Crossmint lets companies harness their power with ease.

Crossmint is a one-stop-shop developer platform for building modern financial applications, from the next generation of fintechs to applications that leverage AI agent–driven commerce.

With just a few lines of code, developers can integrate programmable wallets, stablecoin payments, tokenization, on / off ramps, compliance, and agentic commerce tools — all from a single vendor, without the need for a large team of blockchain engineers.

From companies like MoneyGram and Visa to entire nation states, our more than 40,000 clients use Crossmint to launch new financial products, tokenize assets, and build applications for agentic commerce — all on fully managed infrastructure across 50+ chains.

If you want to help build the backbone of programmable finance and agentic systems, we'd love to work with you!

Location

US, Latin America, or Spain. Candidates must confirm they are able to work in alignment with ET / EST business hours.

Type of employment

Contractor role (20-40 hours per week).

Initial 3-month engagement, renewable.

Potential to convert into full-time employment.

Compensation

Per-hour setting for the contract duration.

About The Role

We're looking for a Technical QA Engineer to join our team building APIs and SDKs for crypto infrastructure. You'll operate at the intersection of quality assurance and technical support engineering, ensuring our APIs and SDKs are robust, reliable, and intuitive for developers.

Responsibilities

• Quality Assurance : Design comprehensive test plans and cases based on product requirements.
• Execute manual and automated tests across multiple platforms and edge cases.
• Validate end-to-end functionality across Wallets, Payments, and Minting products.
• Document results and proactively communicate issues to engineering teams.
• Technical Support Engineering : Evaluate developer experience for API and SDK integrations.
• Act as a technical escalation point for complex or hard-to-reproduce issues.
• Reproduce, debug, and analyze issues; provide detailed technical insights to accelerate fixes.
• Technical Development : Build and maintain demo applications for testing API / SDK functionality.
• Contribute to internal tools and scripts that improve QA and debugging workflows.

About you

Technical Expertise

Essential : Strong knowledge of REST APIs and SDKs.

Proficiency in one or more modern programming languages (JavaScript / TypeScript, Python, or similar).

Ability to build small apps or prototypes to test integrations.

Big bonus : experience with React or React Native.

Quality Assurance Background

Proven experience writing test plans, test cases, and executing both manual and automated tests.

Familiar with QA methodologies and frameworks (e.g., Postman / Bruno / cURL, Jest, Cypress, etc.).

Problem-Solving Mindset

Skilled at debugging and troubleshooting hard-to-reproduce issues.

Clear and effective communicator, especially when relaying technical details to engineering teams.

Nice to Have

Experience with blockchain technologies, crypto wallets, or payment APIs.

Understanding of developer experience best practices.

Our Principles

Results and delivery : Ship high quality work fast.

Build for the long term : Build scalable, secure, and reliable solutions. Use AI.

Extreme Ownership : Be an effective Directly Responsible Individual (DRI). Be proactive.

Be a team player : Be an effective and kind colleague providing credible challenge. Be present and reliable.

We welcome applications even if you meet around 75% of the requirements; diversity makes us stronger.

We foster a respectful environment, uphold equal opportunity, and do not tolerate harassment, racism, or discrimination.

Please note security and interview practices : Crossmint does not conduct AI-based interviews. Our processes include an initial video call with a team member. Do not share personal identification documents or payments during the interview. Be vigilant for fraud; only apply via official domains : @crossmint.com, @crossmint.io, or @paella.dev.

Please let our Talent Team know if you need any assistance completing forms or participating in the process.

Apply

If you are interested, please apply here.

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