Evan Purkhiser

Senior Software Engineer

August 2017 – Present

Architected and launched Uptime Monitoring product end-to-end from conception to production, designing HTTP request validation with custom headers/body/assertions, real-time status tracking with incident detection and flapping prevention, automated domain ownership verification via RDAP/WHOIS, and comprehensive uptime percentage calculations with timezone-aware downtime tracking.
Led multi-year evolution of Cron Monitoring system processing 15MM+ check-ins daily, architecting Kafka-based clock-tick consumers for distributed processing, implementing volume anomaly-based incident detection with tick-based decision making, and building check-in timeline visualizations with timezone awareness and quantization.
Engineered environment-based monitor muting with 4-stage dual-write database migration strategy ensuring zero-downtime deployment, including bidirectional writes, backfills, constraint updates, and deprecated column removal across production database.
Designed detector-based workflow engine as unified abstraction layer for monitors and alerts, building detector validator framework, lifecycle hooks, query APIs with filtering/pagination, and automatic migration path from legacy monitors to new detector system.

Architected organization-level integrations platform enabling rapid development of third-party integrations, building core infrastructure for OAuth flows, provider serialization, feature detection, and permissions management.
Built Slack integration from ground up with workspace token architecture, message unfurling for issue/incident links, interactive actions (assign/resolve/ignore/archive), DM support, and user identity linking, growing to 20k+ organizations.
Implemented GitHub Enterprise and GitHub Apps integrations with commit linking, code mapping for stack trace source linking, repository management, automatic token refresh, and issue creation workflows.
Developed JIRA/JIRA Server and Bitbucket integrations with issue creation/linking, external form error mapping, field validation, and consistent installation flows across integration types.

Led company-wide React Router 3→6 migration across 750+ files and 100+ route definitions, developing backward-compatible SentryRouteObject abstractions, compatibility shims, and feature flag rollout strategy enabling zero-downtime production deployment.
Spearheaded testing modernization initiative migrating 200+ test files from Enzyme to React Testing Library, establishing new testing patterns focused on user behavior over implementation details and improving test reliability across engineering organization.
Drove TypeScript adoption converting 300+ JavaScript files to TypeScript across critical modules (forms, UI components, settings, authentication), establishing type safety best practices and migration patterns organization-wide.
Refactored legacy codebase converting 100+ class components to functional components with hooks, removing deprecated form systems and unsafe React lifecycle methods, standardizing component patterns across application.
Modernized build infrastructure upgrading Node.js 16→18 LTS, webpack 5, Babel 8, TypeScript 4.x, implementing code splitting and lazy loading for improved initial page load performance.
Led Python 2→3 migration fixing 100+ compatibility issues across integrations, plugins, and tests, correcting byte/string encoding, pickle serialization, and HTTP client usage for cross-version compatibility.

Implemented parsing expression grammar via peg.js producing fully-typed AST for incremental parsing of Sentry's custom event search syntax, with careful attention to DX enabling grammar reusability and maintainability.
Architected global command palette (cmd+k) for navigation and actions, building multi-source fuzzy search across routes, commands, API docs, help articles, and organizations with result ranking and caching.
Migrated saved searches from project-level to organization-level with visibility controls via 4-stage database migration (add columns, backfill, migrate constraints, remove deprecated columns), widening permissions for member access.

Rebuilt entire WebAuthn/Passkey authentication system replacing legacy U2F, implementing passkey enrollment and biometric authentication flows, focus-aware triggers, and upgrading backend to cbor2 protocol support.
Built comprehensive 2FA enforcement system with requirement checks before organization invites, authenticator management UI, sudo modal with WebAuthn support, and recovery code generation.
Implemented SAML2 integration with metadata endpoints, form handling, CSRF exemptions, and error display for SSO provider integration.

Optimized database performance eliminating N+1 queries in monitor serializers through select_related optimizations and refactoring computed properties to reduce database load.
Implemented Redis-based volume history tracking for incident detection with clock-tick decision recording, 15-minute windows, pipeline-based operations, and TTL-based state management.
Executed multi-stage schema migrations for critical tables ensuring zero-downtime deployments through bidirectional dual-write patterns, backfills, and careful constraint management.

Implemented node-canvas backend chart rendering service for email and Slack notifications, enabling shared rendering implementations between backend services and frontend chart components.
Improved CI infrastructure with multi-stage GitHub Actions implementing docker test image caching between unchanged dependencies, reducing build times by 40%.
Built comprehensive form system with 50+ field components including validation, error handling, state management, disabled state propagation, and pretty value formatting.
Enhanced accessibility standards adding comprehensive ARIA labels, semantic HTML elements (nav/header/main), improved keyboard navigation, and proper modal/dialog markup across settings and navigation.

Led Frontend Technical Steering Committee accomplishing complete migration to TypeScript, organization-wide code quality initiatives, React Router modernization, and testing infrastructure improvements across 7+ product teams.
Mentored engineers across teams on SDLC best practices, modern React patterns, TypeScript adoption, testing strategies, and frontend architecture decisions.
Established engineering standards and best practices through 7,400+ commits over 8 years, with peak productivity of 900+ commits annually, demonstrating sustained technical leadership and execution.

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