Valerii Tikhomirov

MindLog - Founder & Primary Engineer

Sep 2019 - present · mindlog.app

Built and evolved a journaling product with major solo ownership across backend, infrastructure, billing, product logic, Telegram integration, and user-facing systems.

• Built and maintained the core product architecture, REST API, database design, SPA, CI/CD workflows, and supporting microservices.
• Executed a high-risk infrastructure and domain migration across hosting environments, including files, database, and environment setup, with a controlled cutover strategy to minimize downtime and protect live user data.
• Designed and implemented layered security protections against sustained brute-force attacks, including rate limiting, IP-based controls, 2FA, session awareness, and proof-of-work captcha; reduced meaningful attack attempts to rare edge cases and eventually stopped the attack campaign.
• Built and evolved billing and subscription flows with a dedicated payment microservice, safe auto-renewal logic, proportional refunds, plan switching, and automated receipt handling.
• Rewrote and modernized a large Telegram bot while upgrading related platform and runtime pieces in a low-test legacy codebase.

Jupiter Soft - Backend / Full-Stack Engineer

Feb 2018 - present · jupiter-soft.com

Worked across several production systems with high backend ownership, including CRM, statistics and push microservices, and a Go-based mobile backend.

Go mobile backend

• Served as the primary backend engineer for a mobile product in the meditation / affirmations space, coordinating with mobile engineers, managers, DevOps, and a separate payments-related backend.
• Implemented business-logic-heavy features, including streak and activity logic for a tree-growth mechanic driven by consecutive usage patterns and recovery rules.
• Optimized a slow dashboard flow in a GraphQL-heavy path and reduced response time from 20+ seconds to around 1 second through caching and SQL-level improvements.
• Worked on subscription-related backend issues, push scheduling logic, timezone normalization, and multilingual email templating, including a reusable Go template library.

Call-center CRM

• Took ownership of a fragile bonus-calculation subsystem with weak legacy architecture and recurring correctness problems.
• Reworked the architecture around raw data preservation and safe recalculation, reducing the risk of irreversible data issues and making recovery from failures possible.
• Improved PostgreSQL-heavy performance in several areas, including query cleanup, indexing, and advanced SQL work for business-critical reporting and calculations.

Statistics and push microservices

• Maintained and evolved multiple supporting backend services in parallel with CRM responsibilities.
• Worked with event collection and aggregation flows, where one service stored raw data and another aggregated it for downstream API consumers.
• Maintained service integrations and SDK support across PHP and Go ecosystems.

Earlier Background

• Poiskvill.ru - built and evolved a custom booking-like platform from the ground up with long-term end-to-end ownership.
• Propeller Ads - internal backend systems, refactoring, optimization, and auditing.
• Dengi Online - AML-related checks, XML integrations, and scoring flows.
• Freelance / smaller web projects - websites, landing pages, and small business systems.