LeetSyncGit

LeetSyncGit is a Chrome browser extension that syncs your accepted LeetCode submissions directly to a GitHub repository with a single click.

It is designed for developers who want a clean, automated, and local-first way to maintain a personal archive of LeetCode solutions without copy-pasting code or giving broad access to their GitHub account.

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1. Project Overview

Most developers practicing on LeetCode eventually want their solutions stored in GitHub:

• for revision
• for interviews
• for sharing progress
• for long-term ownership of their work

LeetCode does not provide a native, secure, one-click way to push accepted solutions to GitHub. Existing tools often:

• require backend servers
• request full GitHub access
• auto-create folders or modify repo structure
• store credentials externally

LeetSyncGit exists to solve this problem with a minimal, transparent, and security-first approach.

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2. Key Features

• Sync accepted LeetCode submissions to GitHub in one click
• Works entirely client-side (Chrome extension only)
• No backend server
• No auto-created folders or nested directories
• One file per problem, pushed to the repository root
• Correct file extensions based on language (.cpp, .py, .java, etc.)
• Repository is selected once and reused
• Token stored only on the local device
• Explicit revoke option

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3. Security Design

Why Personal Access Token (PAT) instead of GitHub OAuth?

GitHub OAuth cannot be safely constrained to a single repository without a backend and complex app registration. Most OAuth-based tools end up requesting broad scopes like repo, which grants access to all repositories.

LeetSyncGit deliberately avoids this.

Why Fine-Grained Personal Access Token?

LeetSyncGit uses GitHub Fine-Grained Personal Access Tokens because they allow:

• Repository-level access (single repo only)
• Minimal permissions (Contents: Read & Write)
• No access to issues, workflows, or other repos
• No OAuth redirect flow
• No backend storage

This approach follows the principle of least privilege.

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4. Tech Stack

• Chrome Extension (Manifest V3)
• Vanilla JavaScript
• Chrome APIs
  • chrome.storage.local
  • chrome.runtime
  • chrome.webRequest
  • MutationObserver
• GitHub REST API
• Authentication Model
  • Fine-Grained GitHub Personal Access Token
  • Stored locally in browser storage

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5. Installation (Manual via GitHub)

1. Download the project from GitHub

Option A: Download ZIP

• Go to your GitHub repository

• Click Code → Download ZIP

• Extract the ZIP to a folder on your system

Option B :

• Clone this repository:

  git clone https://github.com/<your-username>/LeetSyncGit.git

2. Open Chrome and go to:

   chrome://extensions
   

3. Enable Developer mode (top right)

4. Click Load unpacked

5. Select the cloned LeetSyncGit directory

The extension will now appear in your Chrome toolbar.

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6. Generate a GitHub Personal Access Token (Required)

LeetSyncGit requires a Fine-Grained Personal Access Token.

Steps

1. Go to:

   https://github.com/settings/personal-access-tokens/fine-grained
   

2. Click Generate new token

3. Configure the token:

   • Token name: LeetSyncGit
   • Expiration: Your choice (recommended: 90 days or more)
   • Resource owner: Your GitHub account

4. Repository access

   • Select Only select repositories
   • Choose the repository you want to sync LeetCode solutions to (you must create this repository first)

5. Permissions

   • Repository permissions:

     • Contents → Read and Write

   • Leave everything else as No access

6. Generate the token and copy it once (GitHub will not show it again)

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7. Configure the Extension

1. Click the LeetSyncGit extension icon

2. Click Connect GitHub

3. Paste the Personal Access Token when prompted

4. Select the repository (one-time selection)

5. The extension will remember:

   • Your token
   • Selected repository
   • GitHub username

No further setup is required.

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8. Common Mistakes and How to Avoid Them

• Token has no repo access

  • Ensure repository access is explicitly selected when creating the token

• Wrong permissions

  • Only Contents: Read & Write is required

• Trying to sync before Accepted

  • Sync only works after an Accepted submission

• Multiple tabs

  • Sync from the tab where the accepted submission is visible

• Token expired

  • Regenerate and reconnect via the extension

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9. Security Limitations and Trade-offs

• The token is stored locally in chrome.storage.local
• Anyone with access to your browser profile could theoretically extract it
• There is no encryption layer (by design, to keep the system simple and auditable)
• OAuth is intentionally not supported to avoid over-privileged access

This is a conscious trade-off in favor of transparency and user control.

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10. Future Improvements

• Optional preview before sync
• Automatic sync toggle
• Support for multiple repositories
• File overwrite strategy selection
• Commit message customization
• Better handling of resubmissions

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12. Contribution Guidelines

Contributions are welcome.

Before submitting a PR:

• Follow the existing project structure
• If you want to contribute to this project, please fork the repository and submit a pull request with clear details of your changes.
• Do not introduce backend services
• Do not add broad GitHub permissions
• Keep security implications explicit
• Test against multiple LeetCode problems (especially edge cases)

Open an issue before large changes to discuss design decisions.

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License

MIT License

If you want, I can also:
- tailor this README for a public open-source release
- shorten it for Chrome Web Store listing
- add a threat model section
- review it from a recruiter’s perspective