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[Position]: Backend Developer — Java / Spring Boot, API bug fixing & REST API development
[Programming Languages]: Java 17, SQL, TypeScript, JavaScript (Vue 3)
[Years Experience]: 7 months, production ERP (Java/Spring Boot, incident resolution, SQL diagnostics)
[Previous Projects]: Multi-tenant financial management API — 34 endpoints across 7 controllers, RBAC with 5 roles, per-company tenant isolation, JWT in HttpOnly cookies, Flyway migrations, soft delete for auditable history. github.com/MatheusCristophi/ERP-Financeiro-Backend · github.com/MatheusCristophi/ERP-Financeiro-Fontend. Production ERP: log and data-driven diagnosis, root-cause tracing, fix and ship. Commit explains what was actually wrong, not a try/catch on the symptom.
[Availability]: Weekdays 18h–23h UTC-3 (overlaps US East afternoons) and weekends, up to 25h/week. Reply within 3h. Async and text-first — written English only, so nothing gets lost in a call.
[Other Info]: Fixes: 500s, NullPointer, unhandled exceptions, bogus 401/403, JWT and Spring Security misconfig, broken role checks, N+1 and missing indexes, data repair via SQL (PostgreSQL, Firebird). Builds: REST APIs with Spring Security, JWT, RBAC, Flyway migrations, DTO layer, third-party integration, Docker, JUnit/Mockito. Written scope and deadline before any code; fixes 50% on approval / 50% on delivery, builds 40/40/20. Diagnosis $30–40/h (1h min, quote before changes). APIs from $350. github.com/MatheusCristophi · linkedin.com/in/matheuscristophi · DM or matheuscr909@gmail.com
[Position]: Backend Developer — Java / Spring Boot, API bug fixing & REST API development
[Programming Languages]: Java 17, SQL, TypeScript, JavaScript (Vue 3)
[Years Experience]: 7 months, production ERP (Java/Spring Boot, incident resolution, SQL diagnostics)
[Previous Projects]:
- Multi-tenant financial management API — 34 endpoints across 7 controllers, RBAC with 5 roles, per-company tenant isolation, JWT in HttpOnly cookies, Flyway migrations, soft delete for auditable history. github.com/MatheusCristophi/ERP-Financeiro-Backend · github.com/MatheusCristophi/ERP-Financeiro-Fontend
- Production ERP: log and data-driven diagnosis, root-cause tracing, fix and ship. Commit explains what was actually wrong, not a try/catch on the symptom.
[Availability]: Weekdays 18h–23h UTC-3 (overlaps US East afternoons) and weekends, up to 25h/week. Reply within 3h. Async and text-first — written English only, so nothing gets lost in a call.
[Other Info]: Fixes: 500s, NullPointer, unhandled exceptions, bogus 401/403, JWT and Spring Security misconfig, broken role checks, N+1 and missing indexes, data repair via SQL (PostgreSQL, Firebird). Builds: REST APIs with Spring Security, JWT, RBAC, Flyway migrations, DTO layer, third-party integration, Docker, JUnit/Mockito. Written scope and deadline before any code; fixes 50% on approval / 50% on delivery, builds 40/40/20. Diagnosis $30–40/h (1h min, quote before changes). APIs from $350. github.com/MatheusCristophi · linkedin.com/in/matheuscristophi · DM or matheuscr909@gmail.com
Java / Spring Boot — API bug fixing & REST API development
500s, hanging endpoints, slow queries, broken auth? I read the logs, trace the flow and fix the root cause — not a try/catch on the symptom.
Production ERP background, where downtime costs money by the minute. Diagnosis through logs and data, fix, and a commit that explains what was actually wrong.
Fixing & maintenance:
- 500s, NullPointer, unhandled exceptions
- Endpoints returning bogus 401/403
- JWT and Spring Security misconfiguration, broken role checks
- N+1 queries, missing indexes, slow endpoints
- Data inconsistency repair and recovery via SQL (PostgreSQL, Firebird)
Building:
- REST APIs with Spring Security, JWT and RBAC
- PostgreSQL with JPA/Hibernate, versioned Flyway migrations, DTO layer
- Third-party API integration, Resilience4j rate limiting
- Vue 3 + TypeScript frontend wired to your API
- Docker environment, JUnit/Mockito tests
How I work:
- Written scope and deadline before a single line of code — in and out of scope, in writing
- Fixes: 50% on quote approval, 50% on delivery. Builds: 40% on approval, 40% at first working deploy, 20% on delivery
- Everything over text, async-friendly. Written English only, so nothing gets lost in a call.
- Repo with clean commits and README, reply within 3h
Overlaps full US business hours (UTC-3, until 6pm local).
Projects: multi-tenant financial API (34 endpoints, RBAC 5 roles, JWT HttpOnly cookies, Flyway, soft delete).
Java 17, Spring Boot, Spring Security, JPA/Hibernate, PostgreSQL, Firebird, Flyway, Resilience4j, Vue 3, TypeScript, Docker, Git.
github.com/MatheusCristophi · linkedin.com/in/matheuscristophi · DM or matheuscr909@gmail.com
Diagnosis $30–40/h (1h min, root cause and fixed quote before any change). APIs from $350, quoted per scope. Send the endpoint list or the stack trace and I'll come back with quote and deadline.
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