SDET- API/Middleware

Welocalize India Llp; United States; Remote; USD 12,000 - 17,000; Full time

Job summary

Welo Global is seeking a highly skilled SDET to perform API and middleware testing, focusing on network analysis, HAR evidence, and replay scripting. The role emphasizes API scripting, protocol-level inspection, and sanitized evidence generation rather than UI automation.

Remote from India with a freelance engagement of 5 weeks at $9.50 per hour, ~35 hours per week. You will collaborate with backend engineers, design test contracts, and maintain test automation for complex middleware services

Qualifications

• 3–5+ years hands-on experience with gRPC-Web, Proto3, HTTP/2, and JSON-RPC/REST
• Proficiency with proxy/traffic inspection tools including Mitmproxy, Charles Proxy, and browser DevTools
• Strong Python scripting and API automation using Postman and cURL

Responsibilities

• Design, build, and maintain automated API test suites covering gRPC-Web, Proto3, HTTP/2, and JSON-RPC/REST based services
• Export clean, sanitized HAR/network evidence whilemaintainingtraceability between UI actions and corresponding network requests.
• Map relevant schemas, headers, identifiers, routing information, and client-injected parameters.
• Use proxy tools such asMitmproxy, Charles Proxy, and browserDevToolssto inspect, intercept, andvalidatenetwork traffic between client and server
• Develop andmaintainAPI automation scripts using Python, Postman, andcURLfor functional and regression testing
• Analyzeprotocol-level request/responsebehaviortoidentifydefects related to serialization, encoding, and transport
• Inspect andvalidaterequest payload structure, including system-level headers (e.g., auth tokens, routing identifiers) and internal/hidden parameters, ensuring correct handling under both valid and malformed conditions
• Collaborate with backend and middleware engineers to define testable contracts and edge-case scenarios
• Continuously improve test automation frameworks for reliability, speed, and maintainability
• Document technical findings, automation coverage, and known protocol-level limitations

Skills

API testing

Network protocol analysis

SDET fundamentals

Python scripting

Tools

Mitmproxy

Charles Proxy

browser DevTools

Postman

cURL

Job description

Job Overview

Welo Global is hiring an SDET (Software Development Engineer in Test) to bring deep technical rigor to middleware-layer testing. This role requires strong technical expertise across gRPC-Web, Proto3, HTTP/2, JSON-RPC/REST, proxy-based traffic inspection, and API scripting. The primary responsibility is to observe and reconstruct the network interactions generated by the onboarding UI, including request/response structures, schemas, headers, identifiers, Enums, and client-injected parameters. This is primarily an API/network analysis and evidence-generation role rather than a conventional UI automation or regression-testing role. The resource will produce sanitized network evidence and controlled, benign tracer replay scripts for downstream backend validation.

Project Details

Title: SDET - API/Middleware

Rate: $9.50/hr

Start Date: 19th October

Duration: 5 Weeks

Commitment: 35 Hours per Week

Location: India (Remote)

Job Type: Freelance

Responsibilities

• Design, build, and maintain automated API test suites covering gRPC-Web, Proto3, HTTP/2, and JSON-RPC/REST based services
• Export clean, sanitized HAR/network evidence whilemaintainingtraceability between UI actions and corresponding network requests.
• Map relevant schemas, headers, identifiers, routing information, and client-injected parameters.
• Use proxy tools such asMitmproxy, Charles Proxy, and browserDevToolsto inspect, intercept, andvalidatenetwork traffic between client and server
• Develop andmaintainAPI automation scripts using Python, Postman, andcURLfor functional and regression testing
• Analyzeprotocol-level request/responsebehaviortoidentifydefects related to serialization, encoding, and transport
• Inspect andvalidaterequest payload structure, including system-level headers (e.g., auth tokens, routing identifiers) and internal/hidden parameters, ensuring correct handling under both valid and malformed conditions
• Collaborate with backend and middleware engineers to define testable contracts and edge-case scenarios
• Continuously improve test automation frameworks for reliability, speed, and maintainability
• Document technical findings, automation coverage, and known protocol-level limitations

Required Qualifications

• Strong hands-onexpertiseof3-5+ yearswithgRPC-Web, Proto3, HTTP/2, and JSON-RPC/REST protocols
• Proficiencywith proxy/traffic inspection tools includingMitmproxy, Charles Proxy, and browserDevTools
• Solid scripting/programming skills in Python, with practical use of Postman andcURLfor API automation
• Experience designing andmaintainingautomated test suites for middleware or API-layer services
• Working understanding of API request structure, including headers, auth tokens, and internal/system parameters, and how to test for their correct handling
• Understanding of software engineering practices as applied to test automation (version control, CI integration, code review)
• Strong debugging skills at the network/protocol level
• Experience analysing browser-generated network traffic and reconstructing API behaviour is strongly preferred.
• Experience with HAR analysis, API schema reconstruction, or controlled API replay is strongly preferred.
• Ability to work within approved staging/test environments and follow defined data-handling and test-authorization requirements isrequired.