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Unlimit

Borderless payment infrastructure provider

Senior Engineer

Site Reliability EngineeringUpdated on Nov 7
Full-timeNo salary listedIn-person

About the Job

Requirements

  • At least 6 years of hands-on card-processing experience covering authorisation, clearing, settlement, chargebacks and reconciliation.
  • At least 2 years in a senior, lead or architect role, with a track record of owning a processing platform and leading engineers directly or as a technical lead.
  • Strong practical experience with SmartVista FrontEnd and/or BackOffice; deep experience with a comparable platform such as Way4 or TranzWare may be considered.
  • Experience improving processes by identifying operational gaps, designing controls and completing remediation plans.
  • Experience certifying with Visa and Mastercard and applying scheme specifications and rules, including ISO 8583, Visa Base I/II and Mastercard IPM/CIS.
  • Hands-on automation skills in Python, SQL or PL/SQL, and Bash; experience with CI/CD tools such as GitLab CI or Jenkins, test automation and API testing tools such as Postman.
  • Practical experience applying AI or machine learning in production, such as anomaly detection, LLM-based tools or agents, or AI-assisted analysis and coding, and understanding of their limits and risks.
  • Working knowledge of Oracle Database, WebLogic, Linux, REST/SOAP web services and HTTP.
  • Experience with scheme tools including Visa Edit Package, VCX, Mastercard File Express and scheme test tools and emulators such as Mastercard MAX and Visa test systems.
  • Good understanding of e-commerce and digital payments, including EMV 3-D Secure, tokenisation (VTS/MDES), Apple Pay, Google Pay, recurring payments and AVS.
  • Knowledge of card technologies and security, including EMV, contactless, Thales HSM, key management and PCI DSS.
  • Experience with release and change management in a 24/7 production environment.
  • Fluent English at B2 level or higher for daily communication with card schemes, vendors and international teams.

Responsibilities

  • Own the end-to-end architecture of the processing ecosystem, including SmartVista FrontEnd and BackOffice, interfaces, HSM and scheme connectivity, and make architecture and technology-stack decisions.
  • Act as technical lead and senior escalation point for processing engineers; set engineering standards and review solutions.
  • Lead major incidents, coordinate responses with internal teams, the vendor and card schemes, and drive post-incident reviews to permanent fixes.
  • Manage the SmartVista vendor relationship for releases, patches, defects and change requests.
  • Map current processing processes—including authorisation, clearing, settlement, disputes, reconciliation, reporting, release and change management, monitoring and on-call—to identify gaps, single points of failure and manual workarounds.
  • Build and execute a remediation plan by defining owners, deadlines and measurable outcomes and following through to closure.
  • Introduce and maintain operational standards, including runbooks, release and change procedures, incident and problem management, SLAs and KPIs such as availability, approval rate and incident resolution time.
  • Track, assess and implement scheme mandates and regulatory changes on time, and document compliance evidence.
  • Deliver technical implementation of new acquiring and issuing card products and services for Visa, Mastercard, UnionPay, American Express and other schemes.
  • Translate scheme mandates and specifications into technical solutions and lead certification projects with the schemes.
  • Configure and develop SmartVista FrontEnd and BackOffice products, services and business rules.
  • Prepare technical requirements for system upgrades, and test and install releases and patches with minimal downtime.
  • Diagnose complex issues across authorisation, clearing and settlement flows and drive them to root cause.
  • Set up and maintain payment-system emulators and test environments, and participate in go-live and pilot activities.
  • Maintain clear technical documentation of the platform and implementation procedures.
  • Design and build an end-to-end monitoring framework for the processing platform, covering infrastructure, applications, interfaces and business metrics.
  • Develop and implement real-time monitoring of authorisation approval and decline rates by scheme, BIN, issuer country, merchant, MCC and response code; response times, timeouts and stand-in processing; scheme, issuer and HSM connectivity and host availability; and transaction volumes and abnormal spikes or drops.
  • Develop and implement monitoring of back-office processes, including clearing-file generation, submission and acknowledgement; incoming scheme files and reports, settlement positions and reconciliation breaks; end-of-day and batch jobs, interchange and fee calculation, and chargeback and dispute deadlines.
  • Monitor scheme-compliance indicators, including decline-code usage, data-integrity edits, excessive retries, and fraud and dispute ratios, to catch issues before non-compliance or fines occur.
  • Define thresholds, alerting rules and escalation paths, and integrate alerts with on-call, incident-management and messaging tools.
  • Build operational dashboards for engineering, operations and management, and define related KPIs and SLAs.
  • Develop health checks, synthetic test transactions and log-based monitoring for SmartVista components.
  • Continuously tune monitoring to reduce false alerts and turn incident findings into new checks and controls.
  • Identify and automate manual and repetitive processes, including reconciliation and settlement, scheme-file exchange and report submission, testing, regression and release management, and monitoring and alerting.
  • Build CI/CD pipelines and automated deployment for processing components and configuration.
  • Design and deliver AI-driven solutions for processing operations, including anomaly detection on transaction flows, decline patterns and fraud signals; intelligent alerting that reduces noise and escalates important events; automated root-cause analysis of declines and incidents; and AI assistants or agents that analyse scheme specifications, mandates and authorisation messages and flag deviations.
  • Introduce test-automation and regression frameworks for scheme messages and processing flows.
  • Promote safe use of AI tools across the team, with controls for data security, PCI DSS and human oversight of production changes.

About the Company

Unlimit

Borderless payment infrastructure provider

Unlimit provides borderless payment services for businesses, helping them operate locally and globally. It runs a large, self-built payment infrastructure that supports accepting payments, sending payments, and managing corporate funds. Companies can issue cards, access alternative payment methods, and handle international transfers through a single platform. The product works as a payment infrastructure-as-a-service: businesses integrate Unlimit’s platform to process payments, issue and manage cards, and settle funds across multiple regions. What sets Unlimit apart is its extensive geographic coverage and wide array of local payment options, enabling companies to enter new markets with ease. Its goal is to support innovative businesses by moving beyond traditional banking, providing a scalable, global financial backend for growth.

Company size
201-500
Company stage
Not listed
Total funding
Not listed
Headquarters
London, United Kingdom
Founded
2009

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