1Before it's built
Understand what will be built, FAST.
Understand agent plans
Your agent wrote a plan. Understand it without reading it.
Agents write plans that run hundreds of lines of markdown, every day. DiffGuardian reads Spec Kit, OpenSpec, Kiro and plain PLAN.md files and turns them into a summary, an architecture diagram, a data model and API tables. Then you ask it questions, by voice or in text, instead of scrolling.
…Grocery Items is the write target: the builder syncs through it, and it has three tasks to build. Nothing is started yet, and the Pantry service is the only new component.
HoldSpaceto askReplay ↺
- 01Requirements, extractedWhat the plan promises, what's missing and what it left open, on one screen.
- 02Diagrams, not paragraphsArchitecture on your real folders, plus a data model and API tables.
- 03Progress at a glanceTasks per component: how much there is to build before it starts, and how far along it is after.
Pro. How Plans works
2While it's being built
Understand what is being built, FAST.
Watch agents in their worktrees
Watch your agent code. Ask what it is doing. See what it could break.
Point agents at their own git worktrees and DiffGuardian follows each one. Its diff and dependency graph update every few seconds as files change, so you can ask by voice what the agent is up to and see the blast radius while it is still working.
…it just added RefundService, which calls PaymentGateway. That puts the webhook handler in its blast radius, and the new test already covers the service.
HoldSpaceto askReplay ↺
- 01Watch it growThe graph of each worktree's changes redraws as the agent writes files.
- 02Ask while it worksHold Space and ask what it is doing, and hear the answer without stopping it.
- 03See the blast radiusWhat its changes reach, before there is a pull request.
Pro. How Worktrees works
3After others built it
Understand what was built by others, FAST.
Talk to your PR
Get a live walkthrough of any PR, out loud, right now.
Hold Space and ask what a PR does. DiffGuardian walks you through it as it goes: the features it ships, what each one changes, what it touches. You hear it while the code it's explaining scrolls into view and is highlighted. Ask a follow-up whenever you like.
…this hunk replaces the hard-coded admin check with a list of actions for each role, so editors can publish but only admins can delete.
HoldSpaceto askReplay ↺
- 01InstantNo setup per PR. Ask and it starts talking.
- 02LiveThe code it's explaining is highlighted and scrolled into view as it talks.
- 03Yours to steerAsk for the part you care about first, or skip to the one file that matters.
Pro. Runs on your own OpenAI or ElevenLabs key, or your system's built-in voice.
4Anywhere in the repo
Understand any part of your entire repo, FAST.
Talk to your codebase
Ask the whole repo a question. Hear the walkthrough. See it on a live graph.
DiffGuardian, available on macOS, Windows and Linux, indexes your repo into a code knowledge graph. Hold Space and ask how auth works or where a webhook is verified. It answers out loud while a live visual of the flow builds on screen, straight from your call graph.
…then authMiddleware asks PermissionService whether that role can perform the action, and answers with a 403 if it can't.
HoldSpaceto askReplay ↺
History · 8
You saidHow does the app decide who can reach the admin routes?
Spoken · 0:22
Every request passes through authMiddleware. It verifies the token, loads the user's role, then asks PermissionService whether that role is allowed to do the action. Admin routes require the admin role. Anyone else gets a 403, and the denial is logged.
▤ Role-based access · on canvas
You typedWhere are the roles defined?
- 01Ask out loudHold Space and ask. No typing, no prompt writing.
- 02Hear it explainedPlain English, with the real files named as it goes.
- 03See the graphThe visual aid builds as it talks.
Prefer typing? The chat is still there.
Trace It
Prefer to read? Trace It gives you the walkthrough at your pace.
Hit Trace It! and a 5,000-line PR becomes a guided tour, one feature at a time, each explained in plain English. Read it as slowly as you like, go back, and approve having seen the whole thing, not skimmed a diff.
- Walkthrough, written — the PR broken into the features it ships, each explained in plain English
- Blast radius — a dependency graph built from the diff alone (heuristic, not AI): every file and module a change actually touches, before it merges
Want it spoken instead? Talk to your PR.
Built for parallel agents
Ten agents, forty PRs. You still know what's shipping.
When agents work in parallel, the bottleneck is you. For every PR, DiffGuardian finds the quickest way for you to understand it, so you spend minutes on each one instead of reading every line or rubberstamping it.
- Read itA written walkthrough, feature by featureTrace It breaks the PR into what it ships and explains each part at your own pace.See how
- Hear itThe same walkthrough, spokenAsk out loud and get it told back, with the code it's explaining highlighted as it goes.See how
- See itA graph of what a change touchesEvery file and module a change reaches, drawn from the diff alone, before it merges.See how
Who it's for
For everyone who needs to know how their products are actually built.
EngineersUnderstand a PR well enough to approve it, without reading every line.
PMsAsk what shipped and get a plain-English answer you can trust, without reading code or waiting for someone to explain it.
Anyone building softwareFounders, designers, QA, analysts, anyone working on an application: ask what the code does and get a plain-English answer, spoken.
Working with a team?
Onboard in minutesA new developer sets up in a few minutes, then talks to the codebase and hears how auth or billing works, with a live graph.
Everyone understands the PRThe author, reviewer and PM each get the walkthrough that suits them: read it, hear it or see it.
PMs ask, engineers keep buildingA PM asks out loud how a feature works and gets a plain-English answer.
Hand-off without the authorInherit an agent-written PR and get the walkthrough instead of waiting on someone's memory.
Your voice, your keys
Your models. Your keys.
Your voice.
Your code never touches our servers.
Bring your own key for Anthropic, OpenAI, Gemini or OpenRouter, or run a local model. Pick a model for each job. Voice runs on your own OpenAI or ElevenLabs key, or your system's built-in voice, and none of it reaches our servers.
- One OpenRouter key reaches ~400 models, with no new account per vendor
- You pay the provider directly, with no markup
- Ollama, LM Studio, llama.cpp and vLLM work out of the box
- Knowledge bases stay on your machine, and credentials sit in your OS keychain
Routing this review through…
Your machinellama-3.3-70b · local
Anthropicnot contacted
OpenRouter~400 models · not contacted
Alongside your PR tools
Your other tools flag things. DiffGuardian helps you understand them, quickly.
| Your PR tools | DiffGuardian, alongside |
|---|---|
| Flag issues and leave comments on the pull request | Explain what the change does, so you can judge the comments |
| Give you text to read | Talk you through it, by voice or in text, highlighting the code as it goes |
| Describe a change in words | Draw what it touches, and build a graph when you ask about the whole codebase |
| Act once the code is written | Also helps before and while it is written: an agent's plan as a summary and diagrams, and its worktree as it codes |
| Use the models the vendor picked, by default | Uses your own models and keys, or fully local, so your code goes only where you send it |
Keep the tools you already use. DiffGuardian sits next to them and gets you to the same understanding in a fraction of the time. It indexes your whole repository into a code knowledge graph and a file index on your machine, so what it tells you is grounded in your real code. See how it fits.
Pricing
Free to start. Upgrade to talk to your code.
Every plan works with local models. Pro adds voice and cloud providers on your own keys. Enterprise, with single sign-on, is coming soon.
Downloads
USD$8/mo
For engineers who want to move fast.
7-day free trial. Cancel anytime.
Try Pro free for 7 days- Everything in Basic
- Voice: talk to your PRs and your codebase
- Unlimited repositories
- Managed AI Providers — BYOK, incl. OpenRouter
- Trace It, Ask, Explain and Polish
- Analyze Project, knowledge bases and RAG
- Plans and Worktrees: understand what agents will build, and are building
- MCP Servers integration
- And many more…
For teams
USD$8/seat/mo
For teams moving fast, working together.
7-day free trial. Cancel anytime.
- Everything in Pro, for everyone
- Centralised seat billing for the whole team
- Seat management and invoicing
- Minimum of 3 seats
Set up by an organisation admin, who buys the seats for the team. Everyone else just downloads the app — individual sign-in happens inside DiffGuardian during onboarding, never here.
Compare plans
Every feature, side by side.
Questions
Your questions, answered.
What does DiffGuardian actually do?
DiffGuardian helps engineers, PMs and anyone building software
understand code as fast as agents write it. It gives you a walkthrough of a pull request one feature at a time, lets you talk to a PR or your whole codebase and hear the answer, and leaves the decision to approve with you.
Can I really talk to a PR?
Yes. On the PR page, hold Space, ask, release, and hear the answer while the lines it discusses are highlighted. Analyze Project has the same push-to-talk in a full-screen overlay, with a graph that builds as the answer is spoken. Voice is a Pro feature.
What's the difference between Trace It and voice?
Trace It turns a PR into a written, feature-by-feature walkthrough that you read at your own pace. Voice (Pro) gives you the walkthrough out loud, live, as soon as you ask, and lets you steer it by asking questions. They are separate features.
Can it keep up with many agents working in parallel?
It is built for that queue: for each PR, DiffGuardian finds the quickest way to help you understand it, whether that is a written walkthrough, a spoken one with the code highlighted, or a graph of what it touches. It speeds up understanding, you approve when you're ready, and it never merges anything.
I'm a PM, not an engineer. Is it for me?
Yes. Ask what a PR or your codebase does and get a plain-English answer out loud, with the code highlighted or a graph of the codebase alongside. You don't need to read code to follow it.
Is it only for solo developers?
No. A new developer can set up in a few minutes and talk to the codebase to learn how it works. The author, reviewer and PM can each get the walkthrough that suits them, and whoever inherits an agent-written PR can get it without waiting on the author.
Where does my voice go?
Straight from your machine to the provider you chose, using your own OpenAI or ElevenLabs key, or it stays with your operating system's built-in voice. Nothing reaches DiffGuardian's servers.
Is my code private?
Your code never reaches a DiffGuardian server. AI features run on your own machine, and cloud models go directly from your machine to the provider whose key you supplied — under your own agreement with them. Because local models are supported on every plan, you can use the AI features without a single line of code leaving your laptop. See the
Security page for the full data-flow breakdown.
Which platforms is DiffGuardian available on?
DiffGuardian is available for macOS, Windows and Linux. The Windows build is an x64 installer that isn't code-signed yet, so Windows may show a SmartScreen warning before you can run it. On Linux, install the .deb or
.rpm package for your distribution — they declare the dependency DiffGuardian's secure key storage needs, so it works out of the box. Use the AppImage only if neither package fits your distribution; it still auto-updates like every other build.
How does billing work, and can I cancel?
Pro starts with a
7
-day free trial for new subscribers. A card is required, and you are charged when the trial ends unless you cancel first. After that Pro is USD $
8
a month, or $
80
a year — two months free. Team is the same price per seat: $
8
a seat a month or $
80
a seat a year, with a minimum of
3
seats. A new Team also starts with a
7
-day free trial. Cancel any time from the billing portal — you keep access until the end of the period you already paid for.
Does this replace the AI tools I already use?
No. Keep them. Tools like CodeRabbit, GitHub Copilot and Greptile flag things on a pull request. DiffGuardian helps the person who approves understand the change quickly, by voice, in conversation and on diagrams. It indexes your whole repository into a code knowledge graph and a searchable file index on your machine, so its answers are grounded in your real code. See how it fits alongside them.