Best tools to understand a codebase in 2026
This is for engineers starting on a codebase they didn't write, and for leads choosing a tool to speed that up. We make Enhanciar, which is one of the options below. We've tried to be fair: several of these are better choices than ours for some teams, and the first section costs nothing.
Start with what's free
- Your IDE's navigation. Go to definition, find references, call hierarchy. Still the fastest way to follow a request through the code.
- Tests and a debugger. Tests tell you what the authors expected; stepping through one real request tells you what actually happens. These were the most repeated tips in Ask HN: How to understand the large codebase of an open-source project?.
- Git history.
git log -L, the pickaxe and blame with the right flags. See git blame alternatives. - An AI coding agent (Claude Code, Cursor, Copilot, Amp) pointed at the repo. Good at “what does this do?”. It sees the code, not the PR or Slack thread where a decision was argued.
The tools, compared
| Tool | What it does | Where it answers | Cites PRs? | Pricing (as of Sep 2026) | Self-hosting |
|---|---|---|---|---|---|
| Enhanciar | Answers “why is this code like this?” from code, PRs, review comments, Slack and docs | Web, Slack, MCP (Claude Code, Cursor) | Yes: file:line plus the PR, review comment or Slack message | Solo $19/mo, Team $80/mo (annual; $24 / $100 monthly), bring your own LLM key, $0 inference markup. Early access by waitlist | No; hosted |
| Unblocked | Codebase Q&A and a context layer for AI agents across code, conversations, issues and docs (source) | Web, Slack, MCP, CLI, API | Says “every answer ships with source links” | $29/user/mo annual or $35 monthly; Enterprise custom; 21-day free trial (source) | On-prem options on Enterprise |
| Sourcegraph (Cody) | Enterprise code search, Deep Search and Cody; Cody Free/Pro ended July 2025 (source) | Web, IDE, MCP server, API, CLI | Cites code; built around search, not PR discussions | Enterprise from $16,000/yr minimum (source) | Yes: self-hosted or single-tenant cloud |
| Glean | Company-wide enterprise search and assistant; its GitHub connector indexes code, PRs, reviews and comments (source) | Web, Slack, MCP (docs) | References source documents, including PRs | Not published; sales-led (source) | Not stated on pricing page |
| Greptile | Mainly AI pull-request review now; codebase context over MCP (source) | PR comments, MCP (Cursor, Claude Code, VS Code, Codex) | Reviews PRs; not a history-of-decisions tool | Free Starter (1 dev, 50 credits); Pro $30/seat/mo; Enterprise custom (source) | Enterprise only |
| Swimm | Code-coupled docs and, now, application-understanding and modernization work for large legacy estates (source) | IDE (VS Code, JetBrains), web, feeds AI tools via MCP (docs) | Checks docs against code on PRs; not a PR-history Q&A tool | Not published; priced by lines of code, via sales (source) | Yes: on-prem and air-gapped |
| Amp | Agentic coding tool; spun out of Sourcegraph as its own company in Dec 2025 | Editor / CLI | It writes code rather than explaining history | Free Hobby tier (BYOK); $20/mo Individual; Enterprise custom (source) | Not listed |
Competitor details come from each vendor's public pages as of September 2026 and are summarised, not quoted. Prices change; check the linked page before you buy. If we got something wrong, email us and we'll fix it.
How to choose
- “Where is X?” across hundreds of repos: Sourcegraph.
- “Why is it like this?” and “what breaks if I change it?”: Enhanciar or Unblocked. Enhanciar is flat-priced with your own model key; Unblocked is per user and offers on-prem on Enterprise.
- “Where is anything at this company?”: Glean.
- “Is this PR safe?”: Greptile.
- “We need written docs that stay current” or a mainframe migration: Swimm.
- “Help me write the change”: an AI coding agent. Pair it with one of the above over MCP so it can see the history too.
When to pick something other than Enhanciar
If you need self-hosting, pick Sourcegraph, Swimm, or the Enterprise plans of Unblocked or Greptile; Enhanciar is hosted only. If you need SSO and procurement paperwork this quarter, the established vendors are further along. If your team won't manage a model key, choose a tool that includes the model. And if your questions are mostly “where”, not “why”, code search is the better buy.
A setup that works for most teams
- Fix the free basics first:
.git-blame-ignore-revsfor format commits, PR templates that ask “why”, and squash merges that keep the PR number. - Pick one tool for “why” questions and connect GitHub plus the chat tool where decisions happen.
- Point your AI coding agent at that tool over MCP, so the agent's changes respect past decisions.
- For a new hire's first week, have them ask the tool before asking a person, and check the cited source each time. The onboarding guide has a fuller plan.
What Enhanciar costs
Solo is $19/month and Team is $80/month on annual billing ($24 and $100 billed monthly). You bring your own model key (Anthropic, OpenAI, Google or a compatible provider) and pay that provider directly; Enhanciar adds $0 on tokens. It is in early access: you join the waitlist and get one email when your invite is ready. There is no self-hosted version.
Related
- Unblocked alternatives
- Swimm alternatives
- Why is this code like this?
- How to understand a legacy codebase fast
- Git blame alternatives
- Onboarding engineers to a large codebase
- Enhanciar vs Glean
FAQ
What is the best tool to understand a large codebase?
There isn't one tool. IDE navigation and a debugger for how it works, code search (Sourcegraph) for where things are, and a tool that reads PRs and chat (Enhanciar, Unblocked) for why it's built that way. (Asked in: Ask HN: How to understand the large codebase of an open-source project?)
Are there AI tools that can make sense of a large repo?
Yes. Coding agents like Claude Code, Cursor and Amp can read a repo and explain it. Tools like Enhanciar, Unblocked and Glean also read PRs, tickets and chat, which is where the reasons live. (Asked in: Ask HN: Any AI tools that help you make sense of a large repo?)
Can I just give the whole codebase to ChatGPT?
For a small repo, roughly. For a large one it won't fit or stay current, and it won't include the review discussions. That's the gap these tools fill. (Asked in: Ask HN: How to share entire codebase with ChatGPT)
Is it safe to connect our private code to these tools?
Read each vendor's data policy. Self-hosted options (Sourcegraph, Swimm, some Enterprise plans) keep code on your infrastructure. With bring-your-own-key tools like Enhanciar, model calls go to the provider whose key you use. (Asked in: Launch HN: Greptile)
Which tools are free?
git, your IDE and a debugger. Greptile has a free Starter plan and Amp has a free Hobby tier (source; source). Unblocked has a 21-day trial.
How do I find why a decision was made in the code?
Go from the line to the commit, from the commit to the PR, and read the review thread and linked ticket. Our guide walks through it.