AtCoder MCP Server

Name: AtCoder MCP Server
Author: ketherworks

by ketherworksversion 0.1.0i★ 0iRuns in the cloud

Registry nameio.github.ketherworks/atcoder

How to install

What it does

Search AtCoder problems and fetch public problem statements through MCP.

Connects Runs in the cloud
Account or key No key needed
Category Search & AI memory

Install

Pick the AI app you use, then copy the settings.

Passed 4/4 checks · What you ask goes through the maker’s server (api.ksrnyx.top)

First: which AI do you use?

ClaudeWeb · app · phoneChatGPTWebClaude CodeTerminalCursorCode editorVS CodeCode editorOtherOther apps

Pick your app and the steps appear below.

Works with Claude · about 2 min

No key, nothing to install · Set it up once on claude.ai or the desktop app, then use it in chat · free accounts can add 1 · on Team/Enterprise an Owner adds it

Open Claude’s Connectors page
CustomizeConnectors
Done
Click “+ Add” → “Add custom connector” and fill in these 2 fields
Copy each value into the field with the same name in Claude, then click Continue
Name · NameAtCoder MCP Server
Remote MCP server URL · Addresshttps://api.ksrnyx.top/oj-mcp/atcoder/mcp
Leave Authentication as Claude detected it, then click Add
Done
Turn it on in a chat
+ConnectorsAtCoder MCP Server
Done
Try it
Use AtCoder MCP Server and tell me what you can do for me, then show me one thing
✓ If Claude says it is using AtCoder MCP Server or shows a AtCoder MCP Server tool in the answer, you are connected

Menu names checked against Anthropic’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with ChatGPT on business plans only

ChatGPT Business, Enterprise or Edu on the web, added by a workspace admin or owner · On Free, Plus or Pro: your ChatGPT plan cannot connect MCP yet

Open ChatGPT’s add-MCP page on the web
Plugins+Add custom MCP server
Done
Fill in the name and address
Enter a name, paste the address under Connection, tick the risk warning and click Create as a plugin
Name · NameAtCoder MCP Server
Connection · Addresshttps://api.ksrnyx.top/oj-mcp/atcoder/mcp
Done
Pick AtCoder MCP Server in a chat
Start a new chat and pick AtCoder MCP Server from your plugins before typing
Done
Try it
Use AtCoder MCP Server and tell me what you can do for me, then show me one thing
✓ If ChatGPT says it is using AtCoder MCP Server or shows a AtCoder MCP Server tool in the answer, you are connected

Menu names checked against OpenAI’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with Claude Code · about 2 min

No key, nothing to install

Open Terminal
Mac: press Command+Space and type Terminal · Windows: open PowerShell
Done

Paste this command and press Enter

claude mcp add --transport http --scope user atcoder https://api.ksrnyx.top/oj-mcp/atcoder/mcp

Done

Type /mcp in Claude Code
You should see AtCoder MCP Server listed as connected
Done
Try it
Use AtCoder MCP Server and tell me what you can do for me, then show me one thing
✓ If Claude Code says it is using AtCoder MCP Server or shows a AtCoder MCP Server tool in the answer, you are connected

Menu names checked against Anthropic’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with Cursor · about 2 min

No key, nothing to install

Click this button to open Cursor
Open in Cursor
Cursor asks you to confirm; click Install
Done
Open the AI chat in Cursor in Agent mode
Done
Try it
Use AtCoder MCP Server and tell me what you can do for me, then show me one thing
✓ If Cursor says it is using AtCoder MCP Server or shows a AtCoder MCP Server tool in the answer, you are connected

Menu names checked against Cursor’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Works with VS Code · about 2 min

No key, nothing to install

Click this button to open VS Code
Open in VS Code
VS Code asks you to confirm; click Install
Done
Open the AI chat in VS Code in Agent mode
Done
Try it
Use AtCoder MCP Server and tell me what you can do for me, then show me one thing
✓ If VS Code says it is using AtCoder MCP Server or shows a AtCoder MCP Server tool in the answer, you are connected

Menu names checked against VS Code’s help page on Nov 11, 2026 · your screen may differ slightly by app version

Other apps that use MCP, such as Windsurf, Zed or Gemini CLI, each add servers differently. See how in the app list.

See every app that uses MCP →

Address for apps that connect over the web

Addresshttps://api.ksrnyx.top/oj-mcp/atcoder/mcp

JSON settings are under “For developers” below

Stuck? Ask people who use AtCoder MCP Server💬 Discussion →

For developers: Terminal commands and JSON settings

Over the web

Claude Code

claude mcp add --transport http --scope user atcoder https://api.ksrnyx.top/oj-mcp/atcoder/mcp

Cursor (~/.cursor/mcp.json)

{
  "mcpServers": {
    "atcoder": {
      "url": "https://api.ksrnyx.top/oj-mcp/atcoder/mcp"
    }
  }
}

VS Code (mcp.json)

{
  "servers": {
    "atcoder": {
      "type": "http",
      "url": "https://api.ksrnyx.top/oj-mcp/atcoder/mcp"
    }
  }
}

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

At a glance

GitHub stars i: 0
Downloads per weeki: Not on npm/PyPI
Licence i: No licence stated
Connection: Runs in the cloud
Transport: streamable-http
Latest versioni: 0.1.0
Categoryi: Search & AI memory
Published to registryi: Jul 21, 2026
Code last changedi: Sep 8, 2026
Maker: ketherworks
Repo: ketherworks/atcoder-mcp-server
Registry status: Active

Which apps can use it

Based on how this server connects and on each app’s own docs, checked Nov 10, 2026.

Connect over the internet in

Claude ChatGPT Goose LM Studio Msty Studio Cherry Studio Cursor VS Code + GitHub Copilot Visual Studio Windsurf (Devin Desktop)Zed Kiro Cline Continue JetBrains AI Assistant Claude Code Codex CLI Gemini CLI OpenCode nodecode Warp LibreChat Open WebUI Raycast

All apps, with pros and cons →

What it can do

Tool names and descriptions exactly as the server reported them on Nov 11, 2026. The maker wrote them, not us; we show them as plain text.

oj_capabilities
Report the audited anonymous AtCoder read surface and explicitly unsupported operations.
oj_health
Report local readiness and the latest observed AtCoder page-read status without probing upstream.
oj_fetch_problem
Fetch one public problem statement from an exact contest/task pair or canonical atcoder.jp task URL. Returns sanitized HTML with preserved math, samples, limits, hashes, and source provenance.
oj_search_problems
Resolve exactly one contest/task id, atcoder:contest/task id, or canonical task URL. Free-text and catalog crawling are not supported.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 12, 2026

✓ Pass
Maker matches the repo
The registry name was verified with the GitHub account ketherworks, which owns the repo
✓ Pass
Still maintained
Code last changed 2 months ago
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
✓ Pass
Endpoint responds
Responded in 92 ms (HTTP 200)
– Not applicable
Sign-in with OAuth
No sign-in needed
✓ Pass
No hidden instructions in tool descriptions
Read 4 tool descriptions and found no hidden instructions to the AI

Discussion

Ask, share a tip or report that it does not work. Sorted by what people marked helpful.

No posts yet. Be the first to ask or share.

Posts here are written by users, not the PopNx team.

User reviews

No reviews yet

Compared with others in Search & AI memoryi

More stars than 0% of the other 5974 servers in this category
Published to the registry more recently than 22% of the other 5974 servers in this category
Basic checks equal to or better than 100% of the other 5974 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is AtCoder MCP Server safe?

It passed 4 of 4 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs in the maker’s cloud. Connect over the internet with nothing to install, but what you send passes through the maker’s servers.

Is it still maintained?

The GitHub repo last changed 2 months ago, and the latest version (0.1.0) reached the registry 4 months ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT Business and above.

What can I use instead?

In the same category: Context7, Codebase Memory, Ruflo

Others in the same category

Servers in the same category from other makers, sorted by stars.

Reading a card:↓ Downloads per weeki★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

Context7

Feeds AI the latest docs for libraries and frameworks before it answers, so code it writes does not use outdated, removed functions.

by upstashWidely used↓ 1.2M/wk★ 64.6KUpdated 3 days ago

Computer or cloud

Install

Codebase Memory

Codebase knowledge graph for AI agents — 162 languages, sub-ms queries, 99% fewer tokens.

by DeusDataWidely used↓ 16.8K/wk★ 48.5KUpdated 26 days ago

Runs on your computer

Install

Ruflo

Agent teams, swarms, memory and hooks for Claude Code and Codex, served over MCP.

by ruvnetWidely used↓ 74.3K/wk★ 81.5K Stars for the whole repoUpdated yesterday

Runs on your computer

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

AtCoder MCP Server

简体中文

Find and read past AtCoder problems through MCP, locally or over hosted HTTP.

Quick Start

Add the hosted server to your MCP configuration:

"servers": { "atcoder": { "type": "http", "url": "https://api.ksrnyx.top/oj-mcp/atcoder/mcp" } } }

The endpoint accepts anonymous read requests. It does not need an API key, Cookie, or judge account.

Then ask:

Fetch AtCoder problem abc086_a and show its samples.

What It Can Do

Tool	Purpose
`oj_capabilities`	Report the available AtCoder read operations and transport.
`oj_health`	Report process readiness and the latest upstream read.
`oj_fetch_problem`	Fetch one past problem by canonical URL or contest/task id.
`oj_search_problems`	Resolve an exact task URL or contest/task identifier.

Run Locally

Requires Node.js 22 or newer.

npm ci

npm run check npm run build node packages/atcoder/dist/index.js

MCP client configuration from a source checkout:

"servers": { "atcoder": { "type": "stdio", "command": "node", "args": ["/absolute/path/packages/atcoder/dist/index.js"] } } }

Tagged GitHub releases attach a standalone npm tarball.

Availability

Hosted MCP: https://api.ksrnyx.top/oj-mcp/atcoder/mcp
Official MCP Registry: io.github.ketherworks/atcoder, described by server.json
Health status: see the repository homepage or call oj_health

Source and Safety

This standalone release is generated from the reviewed Competitive Programming MCP source. The release package bundles the shared OJ contract implementation, so its runtime does not depend on unpublished workspace packages.

Platform Rules

Do not use this server during ongoing ABC, ARC, or AGC contests. AtCoder's current generative-AI rules generally prohibit that use. This project is intended for practice with past problems. It is unofficial and is not affiliated with or endorsed by AtCoder Inc. Problem content remains subject to the AtCoder Terms of Use.

The server exposes no run or submit tool. It accepts no judge account credentials. See SECURITY.md for the security boundary and PROVENANCE.md for the canonical source revision.

Development

npm ci

npm run check npm run pack:check npm run deploy:dry

License

Adapter source code is MIT licensed. Judge problem content and trademarks are not relicensed by this repository.

AtCoder MCP Server

What it does

Install

Open Claude’s Connectors page

Click “+ Add” → “Add custom connector” and fill in these 2 fields

Turn it on in a chat

Try it

Open ChatGPT’s add-MCP page on the web

Fill in the name and address

Pick AtCoder MCP Server in a chat

Try it

Open Terminal

Paste this command and press Enter

Type /mcp in Claude Code

Try it

Click this button to open Cursor

Open the AI chat in Cursor in Agent mode

Try it

Click this button to open VS Code

Open the AI chat in VS Code in Agent mode

Try it

Over the web

At a glance

Which apps can use it

Related guides

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Discussion

User reviews

Compared with others in Search & AI memoryi

Common questions

Others in the same category

Context7

Codebase Memory

Ruflo

README from the maker

AtCoder MCP Server

Quick Start

What It Can Do

Run Locally

Availability

Source and Safety

Platform Rules

Development

License