Igor Kasyanchuk
Igor Kasyanchuk is an independent Ruby on Rails developer, open-source maintainer, and solo creator who builds web applications, developer tools, and open-source gems. His DiffNotes project helps coding agents explain pull-request changes beside the diff, with screenshots and live demos, while preserving a self-hosted option for teams.
At a Glance
- Software development teams using AI coding agents
- Teams reviewing pull requests on GitHub, GitLab, or Bitbucket
- Organizations needing self-hosted or invite-only code-review context
- Ruby/Rails developers and open-source maintainers
- +1 more
AI Tools by Igor Kasyanchuk
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DiffNotes
Agent PR Annotations in Diffs
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Latest News
DiffNotes 1.8.0/1.8.1: public live demo without an account, prebuilt amd64/arm64 GitHub Container Registry image, higher account limits, and mobile/deployment fixes.
DiffNotes 1.7.0: onboarding split into read-notes and write-notes paths, one-command agent setup, automatic extension connect page, and improved GitHub invitation flow.
DiffNotes 1.6.1: security hardening for invitations, sessions, request bodies, login throttling, token storage, previews, demos, and agent-skill execution.
DiffNotes 1.6.0: notes can follow moved code, diff blocks and measurement tables were added, and note detail/style controls expanded.
Products & Services
Open-source MIT server, web app, agent skill/MCP endpoint, and browser extension that lets a coding agent annotate pull requests with explanations, risk levels, screenshots, recordings, file previews, reports, and sandboxed HTML demos. Notes appear inside diffs on GitHub, GitLab, and Bitbucket without posting comments to the PR; users can use diffnotes.dev or self-host it.
Free MIT macOS workbench for running multiple coding agents side by side, giving each task its own Git worktree, terminal, live status, browser preview, PR checks, SSH hosts, and phone access.
Free MIT self-hosted image host for pull-request screenshots built for AI coding agents; an agent uploads with curl and receives a public URL and ready-made Markdown.
A tool that turns a developer's complete GitHub contribution history into a visual biography, highlighting open-source pull requests and producing shareable images.
Market Position
DiffNotes positions itself as complementary to, rather than another, automated review bot: the agent that authored the change explains intent and trade-offs beside the diff, while nothing is posted to the pull request. Its differentiators are agent-native annotations, screenshots and sandboxed demos, GitHub/GitLab/Bitbucket coverage, open-source MIT licensing, a free hosted service, and self-hosting. The adjacent competitive set is conventional PR review bots and code-review platforms, but DiffNotes emphasizes author-context and zero PR noise instead of external review comments.
Leadership
Founders
Igor Kasyanchuk
Ruby on Rails developer and Tech/Team Lead from Ukraine; GitHub describes him as working with Ruby since 2009 (after earlier C++ and Java development), and his personal site identifies him as a builder of Rails applications and open-source gems. He maintains projects including rails_db, rails_performance, active_storage_validations, Prunto, and DiffNotes.
Executive Team
Igor Kasyanchuk
Independent developer, creator, and maintainer
Ruby on Rails developer from Ukraine, working with Ruby since 2009; GitHub lists him as a Ruby on Rails Tech/Team Lead and his LinkedIn search profile describes Ruby on Rails architect/team-lead work managing a 15-person team. He created and maintains DiffNotes and a broad portfolio of Rails and AI-agent tools.
Founding Story
DiffNotes was created by Igor Kasyanchuk around the idea that the coding agent that wrote a change still knows the intent, trade-offs, and testing context. Instead of another review bot posting comments to a pull request, the agent uploads plain-language explanations, risk markers, screenshots, reports, and small demos to a DiffNotes server, where a browser extension places them beside the changed lines. The project also provides self-hosting so code context can remain on a team's infrastructure.
Business Model
Revenue Model
DiffNotes is free and open source under MIT, with a free hosted service at diffnotes.dev and a self-hosted Docker deployment option. The official site explicitly says diffnotes.dev has no paid plan; the project can be run commercially on a user's own infrastructure.
Pricing Tiers
Free hosted server; accounts hold up to 10,000 pull requests and 1 GB of files, with notes/files deleted 365 days after a pull request's last upload by default.
Run the open-source container on a Docker host or supported deployment platform; infrastructure costs are paid by the operator.
Target Markets
- Software development teams using AI coding agents
- Teams reviewing pull requests on GitHub, GitLab, or Bitbucket
- Organizations needing self-hosted or invite-only code-review context
- Ruby/Rails developers and open-source maintainers
- Individual developers running coding agents locally on macOS
- Speeding up code review by explaining why a coding agent changed each block
- Reviewing AI-generated UI changes with screenshots, recordings, and clickable demos
- Surfacing high-risk changes involving money, authentication, migrations, or deployment
- Keeping PR review context out of public PR comments and notification streams
- Self-hosted review context for teams whose code cannot leave their infrastructure
- Annotating pull requests across GitHub, GitLab, and Bitbucket