Ivan Zemchikov

Profile:

Ruby on Rails / Full-stack developer with commercial experience building and maintaining a complex B2B platform in the real estate finance / loan servicing domain.

My main focus is backend development with Ruby on Rails, complex business logic, financial calculations, payment workflows, document generation, external API integrations, reporting, reconciliation, alerts, and legacy code modernization.

On my main long-term project, I work with business-critical areas of the system: payment schedules, default interest, ACH/Wire payments, monthly statements, investor reporting, borrower-facing functionality, DocuSign signing flows, Slack/Dropbox/email integrations, and document workflows.

I am comfortable working with large existing codebases, translating complex operational rules into maintainable Rails architecture, covering business logic with tests, and improving production systems without breaking existing workflows. All team communication — tasks, code reviews, and discussions — is conducted in English.

Work Experience:

Continure, Milwaukee, Wisconsin, USA
Ruby on Rails / Full-stack Developer
2022 — Present · Remote

I work at Continure on Ruby on Rails projects for the U.S. market. My main long-term project is Domcap / Real Estate Finance Platform: a large B2B portal for a New York real estate finance / loan servicing business.

Since late 2022, I have been continuously developing Domcap: implementing business logic, payment workflows, document management, DocuSign signing flows, investor/business entity functionality, reporting, alerts, reconciliation, and external service integrations. An open work diary maintained since March 2023 is available here.

Key responsibilities:

• Develop and maintain a Ruby on Rails application for real estate finance / loan servicing operations.
• Implement complex financial business logic: payment schedules, default interest, partial payments, cure periods, fees, monthly statements, credit lines, REO/foreclosure workflows.
• Build payment workflows: ACH payments, Wire payments, approval flows, Construction Draw payouts, monthly mass payments, revocation logic, and duplicate-prevention rules.
• Integrate external APIs: DocuSign, Slack, Dropbox, Plaid, Western Alliance Bank, HouseCanary, Google API, OpenAI/internal tooling.
• Build document workflows: DOCX/PDF generation, Dropbox editing, e-signature flows, automatic signed-document uploads, Slack/email notifications.
• Modernize legacy UI: Bootstrap 3 to Bootstrap 5, jQuery/best_in_place to Turbo/Stimulus, Vue.js to Rails/Hotwire when it improves maintainability.
• Design Rails models, controllers, services, background jobs, Pundit policies/scopes, and REST-friendly controllers.
• Write RSpec tests for models, services, request specs, business logic, and external API integrations.
• Develop and maintain js-file-tools-api — an internal Node.js microservice for file processing with Dropbox API, Google API, and main Rails application integration.
• Work with large reporting tables: filters, sorting, grouped columns, sticky headers, and CSV export.
• Investigate production edge cases and fix issues in financial logic, permissions, integrations, and user workflows.

Key achievements:

• Reworked core Payment Schedule and Default Interest logic: implemented new rules for default interest accrual, partial payments, unpaid due amounts, cure periods, paid date behavior, and manual overrides.
• Built Monthly Mass Payments / Bulk Jobs workflow: auto-generated monthly pages, upcoming/late/default payment rows, bulk pull/revoke actions, monthly statements, ACH approvals, borrower emails, Dropbox editing, editable email templates, and duplicate-payment prevention.
• Built Western Alliance Bank API integration and implemented Wire payments infrastructure: creation, confirmation, approval/review flow, bulk approve/reject actions, post-approval processing, and Wire payouts inside the Construction Draw workflow.
• Improved WAB API failure support by storing x_correlation_id in the ActiveRecord model, allowing bank support to identify failed wire requests.
• Implemented Google API integration for interactive charts and financial data visualization on reporting pages.
• Developed and maintained js-file-tools-api — an internal Node.js microservice for file processing: built its integration with Dropbox API, Google API, and the main Rails application.
• Built DocuSign API integration and document signing workflows for Payoff Letter, Default Letter, Term Sheet, and other documents: multi-stage process, signer changes, envelope revocation, webhook-based status tracking, automatic signed-document uploads, Slack/email notifications.
• Built and improved Payoff Letter workflow: Generate → Edit/Review → Approve → Signing → Complete, borrower-facing sending options, per diem / total due / interest calculation fixes, wire vs check options, and fee inclusion rules.
• Implemented Default Letter approval/signing workflow with 9 template types and repeatable approval/signing cycles.
• Built Loan Tape reporting page: 40 metric columns, 9 column groups, 22 sortable fields, 5 filters, CSV export, and a robust sticky header that works with filtering, sorting, and horizontal scrolling.
• Modernized Investor / Business Entity portal: rebuilt Investor Roll, Business Entity pages, investor-specific workflows, Capital Manager pages, and capital records flows, moving major UI sections to Bootstrap 5.
• Created Credit Line Analysis & Reconciliation module: credit line capacity/drawn/available tracking, deal-level allocations, snapshots, end-of-month averaging, and integration of computed credit balances into deal/payment pages.
• Implemented Plaid reconciliation tooling: separate Incoming/Outgoing views, filterable tables, mapping transactions to deals, and allocating one transaction across multiple targets such as principal, interest, default interest, fees, and other categories.
• Implemented automated HouseCanary valuation mismatch alerts: automatic address analysis when a deal moves from Term Sheet, comparison of aggregate value with As-Is Value, Slack alerts, and user tasks when the difference exceeds 10%.
• Built alerts/notifications platform improvements: maturity notifications, insurance expiry alerts, Alerts Manager UI, enable/disable controls, global editable templates, Slack/email options, and per-deal visibility.
• Reworked Document Manager: added audit trail, fixed role-based visibility, implemented complex Pundit policies/scopes for employees and clients, and improved REST controller structure.
• Replaced legacy best_in_place across the project with a custom Turbo inline editor component, touching multiple pages and 11 controllers.
• Implemented support for multiple developers per deal instead of the previous single-developer model. Propagated this cross-cutting change through deal show page, Loan Tape, AML/KYC, Cash Flow, Term Sheet, Proof of Funds, Pipeline, Operations, Quick Leads, RD Clients, Due Diligences, global search, Deal Consistency, and Foreclosure pages.
• Added new REO/post-Foreclosure deal status with sale amount/date capture, tax-related behavior, and a new Operations table.
• Improved ACH/payment functionality: bulk actions on ACH approval page, backend sorting, filters with saved user preferences, linking admin-created ACH payments to deals/scheduled payments, and ACH support inside Construction Draw.
• Built borrower-facing Construction Draw public link flow: a manager generates a secure token link, the client creates a Construction Draw request without authorization, and the system notifies the team after submission.
• Implemented daily task summary email batching: user tasks, comments, and updates are accumulated and sent as one daily email instead of many separate emails.
• Migrated Slack file upload integration from deprecated endpoints to the newer Slack upload flow.
• Improved test coverage and maintainability: covered complex financial and permission logic with tests, updated 109 test files, and reduced full test suite runtime by about 40%.

Other projects at Continure:

Loandox — a CRM system for a financial institution built with Ruby on Rails. Participated in feature development and project support.

Holocenter — a website for The Zekelman Holocaust Center in Farmington Hills, Michigan. Participated in Rails development and maintenance.

Skills:

• Ruby
• Ruby on Rails
• RSpec
• MySQL
• PostgreSQL
• SQL
• JavaScript
• Node.js
• Hotwire
• Turbo
• Stimulus
• Vue.js
• HTML
• CSS
• Bootstrap 5
• Git
• REST API
• Background Jobs
• Pundit
• DocuSign API
• Slack API
• Dropbox API
• Plaid API
• Western Alliance Bank API
• HouseCanary API
• Google API
• OpenAI API
• Service Objects
• Query Objects
• CSV Export
• PDF/DOCX generation
• VCR
• FactoryBot
• XML
• JSON
• Linux
• Heroku

Education:

• Ruby on Rails Course
  • Good Programmer — Rails Heliodor 2021 (2021–2022)
• Samara Law Institute of the Ministry of Justice
  • Faculty of Law (1999–2003)

Languages:

• Russian — Native
• English — B2/C1
• Spanish — B1
• German — A1