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PopNx MCPMCP servers for people who use AI · explained in plain words

Uniswap Universal Router Decoder

by Elnarilversion 4.0.0i★ 277iRuns on your computer
Registry nameio.github.Elnaril/uniswap-universal-router-decoder

How to install

What it does

Decode and encode Uniswap Universal Router calldata (V2, V3, V4). Read-only: never signs or sends.

  • Connects Runs on your computer
  • Account or key No key needed
  • Category Crypto & blockchain

Install

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

Passed 3/3 checks · Runs on your computer · ✓ Commands checked Nov 14, 2026

First: which AI do you use?

Pick your app and the steps appear below.

Works with Claude, with some setup first

Install Python (uv) on your computer first (one time) · Only the Claude desktop app (Windows or Mac), not the web or phone

Let AI install it

Copy this message into a Claude chat. The AI checks your computer, tells you which file it will change, and waits for your OK every time.

Please install the MCP server Uniswap Universal Router Decoder for Claude on this computer, in this order: 1) Check uv with uv --version. If it is missing, tell me to install it from https://docs.astral.sh/uv/getting-started/installation/; do not install it yourself. 2) Use only this config (already checked by PopNx MCP): { "mcpServers": { "uniswap-universal-router-decoder": { "command": "uvx", "args": [ "uniswap-universal-router-decoder" ] } } } 3) Tell me the full path of the file you will change, or the command you will run, and wait for my OK. 4) No key is needed. 5) Do what we agreed, then check that the Uniswap Universal Router Decoder tools really show up.

This message has no key in it. If a key is needed, the AI will ask you to paste it yourself into the file or the app’s field.

  1. Install uv (if you don’t have it)

    Already installed? Check first · Open Terminal, type this command and press Enter

    uv --version
    • A version number such as uv … = installed, skip this step
    • "command not found" (on Windows: "is not recognized") = not installed yet, or installed but Terminal needs to be closed and reopened
    How to open Terminal

    Mac: press ⌘ + Space, type Terminal, press Enter

    Windows: open Start, type Windows PowerShell, then Open

    Not installed: uv has no click-through installer. Copy the one-line command for your system (macOS or Windows) from uv’s official page into Terminal · no separate Python install needed; uv downloads it when required

    Open the uv download page ↗

    When it’s done, close Terminal, open it again and run the same command. You should see a version number: uv --version

    Install once; it works for everything that needs uv

  2. Open the Claude desktop app’s settings file

    SettingsDeveloperEdit Config

  3. Paste these settings and save the file

    {
      "mcpServers": {
        "uniswap-universal-router-decoder": {
          "command": "uvx",
          "args": [
            "uniswap-universal-router-decoder"
          ]
        }
      }
    }
  4. Quit Claude and open it again

  5. Try it

    Use Uniswap Universal Router Decoder and tell me what you can do for me, then show me one thing

    ✓ If Claude says it is using Uniswap Universal Router Decoder or shows a Uniswap Universal Router Decoder tool in the answer, you are connected

1 optional setting(s) (works without them)

The command above works without these. Add them only if you want to change something, following the maker’s description.

  • RPC_URL Ethereum RPC endpoint. Optional: only decode_transaction needs it.

Descriptions are as written by the maker.

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

ChatGPT cannot connect Uniswap Universal Router Decoder yet

Uniswap Universal Router Decoder runs on your computer, but ChatGPT can only connect servers that run on the web

What you can do instead

A · Use an app that can connect Uniswap Universal Router Decoder

  • Install Python (uv) on your computer first (one time) · Only the Claude desktop app (Windows or Mac), not the web or phone
  • Install Python (uv) on your computer first (one time)
  • Install Python (uv) on your computer first (one time)
  • Install Python (uv) on your computer first (one time)

B · Others in Crypto & blockchain that work with ChatGPT

Picked from the most used in the same category, only ones that connect by address with no key

Works with Claude Code, with some setup first

Install Python (uv) on your computer first (one time)

Let AI install it

Copy this message into a Claude Code chat. The AI checks your computer, tells you which file it will change, and waits for your OK every time.

Please install the MCP server Uniswap Universal Router Decoder for Claude Code on this computer, in this order: 1) Check uv with uv --version. If it is missing, tell me to install it from https://docs.astral.sh/uv/getting-started/installation/; do not install it yourself. 2) Use only this config (already checked by PopNx MCP): claude mcp add --scope user uniswap-universal-router-decoder -- uvx uniswap-universal-router-decoder 3) Tell me the full path of the file you will change, or the command you will run, and wait for my OK. 4) No key is needed. 5) Do what we agreed, then check that the Uniswap Universal Router Decoder tools really show up.

This message has no key in it. If a key is needed, the AI will ask you to paste it yourself into the file or the app’s field.

  1. Install uv (if you don’t have it)

    Already installed? Check first · Open Terminal, type this command and press Enter

    uv --version
    • A version number such as uv … = installed, skip this step
    • "command not found" (on Windows: "is not recognized") = not installed yet, or installed but Terminal needs to be closed and reopened
    How to open Terminal

    Mac: press ⌘ + Space, type Terminal, press Enter

    Windows: open Start, type Windows PowerShell, then Open

    Not installed: uv has no click-through installer. Copy the one-line command for your system (macOS or Windows) from uv’s official page into Terminal · no separate Python install needed; uv downloads it when required

    Open the uv download page ↗

    When it’s done, close Terminal, open it again and run the same command. You should see a version number: uv --version

    Install once; it works for everything that needs uv

  2. Open Terminal

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

  3. Paste this command and press Enter

    claude mcp add --scope user uniswap-universal-router-decoder -- uvx uniswap-universal-router-decoder
  4. Type /mcp in Claude Code

    You should see Uniswap Universal Router Decoder listed as connected

  5. Try it

    Use Uniswap Universal Router Decoder and tell me what you can do for me, then show me one thing

    ✓ If Claude Code says it is using Uniswap Universal Router Decoder or shows a Uniswap Universal Router Decoder tool in the answer, you are connected

1 optional setting(s) (works without them)

The command above works without these. Add them only if you want to change something, following the maker’s description.

  • RPC_URL Ethereum RPC endpoint. Optional: only decode_transaction needs it.

Descriptions are as written by the maker.

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

Works with Cursor, with some setup first

Install Python (uv) on your computer first (one time)

Let AI install it

Copy this message into a Cursor chat. The AI checks your computer, tells you which file it will change, and waits for your OK every time.

Please install the MCP server Uniswap Universal Router Decoder for Cursor on this computer, in this order: 1) Check uv with uv --version. If it is missing, tell me to install it from https://docs.astral.sh/uv/getting-started/installation/; do not install it yourself. 2) Use only this config (already checked by PopNx MCP): { "mcpServers": { "uniswap-universal-router-decoder": { "command": "uvx", "args": [ "uniswap-universal-router-decoder" ] } } } 3) Tell me the full path of the file you will change, or the command you will run, and wait for my OK. 4) No key is needed. 5) Do what we agreed, then check that the Uniswap Universal Router Decoder tools really show up.

This message has no key in it. If a key is needed, the AI will ask you to paste it yourself into the file or the app’s field.

  1. Install uv (if you don’t have it)

    Already installed? Check first · Open Terminal, type this command and press Enter

    uv --version
    • A version number such as uv … = installed, skip this step
    • "command not found" (on Windows: "is not recognized") = not installed yet, or installed but Terminal needs to be closed and reopened
    How to open Terminal

    Mac: press ⌘ + Space, type Terminal, press Enter

    Windows: open Start, type Windows PowerShell, then Open

    Not installed: uv has no click-through installer. Copy the one-line command for your system (macOS or Windows) from uv’s official page into Terminal · no separate Python install needed; uv downloads it when required

    Open the uv download page ↗

    When it’s done, close Terminal, open it again and run the same command. You should see a version number: uv --version

    Install once; it works for everything that needs uv

  2. Click this button to open Cursor

    Open in Cursor

    Cursor asks you to confirm; click Install

  3. Open the AI chat in Cursor in Agent mode

  4. Try it

    Use Uniswap Universal Router Decoder and tell me what you can do for me, then show me one thing

    ✓ If Cursor says it is using Uniswap Universal Router Decoder or shows a Uniswap Universal Router Decoder tool in the answer, you are connected

1 optional setting(s) (works without them)

The command above works without these. Add them only if you want to change something, following the maker’s description.

  • RPC_URL Ethereum RPC endpoint. Optional: only decode_transaction needs it.

Descriptions are as written by the maker.

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

Works with VS Code, with some setup first

Install Python (uv) on your computer first (one time)

Let AI install it

Copy this message into a VS Code chat. The AI checks your computer, tells you which file it will change, and waits for your OK every time.

Please install the MCP server Uniswap Universal Router Decoder for VS Code on this computer, in this order: 1) Check uv with uv --version. If it is missing, tell me to install it from https://docs.astral.sh/uv/getting-started/installation/; do not install it yourself. 2) Use only this config (already checked by PopNx MCP): { "servers": { "uniswap-universal-router-decoder": { "type": "stdio", "command": "uvx", "args": [ "uniswap-universal-router-decoder" ] } } } 3) Tell me the full path of the file you will change, or the command you will run, and wait for my OK. 4) No key is needed. 5) Do what we agreed, then check that the Uniswap Universal Router Decoder tools really show up.

This message has no key in it. If a key is needed, the AI will ask you to paste it yourself into the file or the app’s field.

  1. Install uv (if you don’t have it)

    Already installed? Check first · Open Terminal, type this command and press Enter

    uv --version
    • A version number such as uv … = installed, skip this step
    • "command not found" (on Windows: "is not recognized") = not installed yet, or installed but Terminal needs to be closed and reopened
    How to open Terminal

    Mac: press ⌘ + Space, type Terminal, press Enter

    Windows: open Start, type Windows PowerShell, then Open

    Not installed: uv has no click-through installer. Copy the one-line command for your system (macOS or Windows) from uv’s official page into Terminal · no separate Python install needed; uv downloads it when required

    Open the uv download page ↗

    When it’s done, close Terminal, open it again and run the same command. You should see a version number: uv --version

    Install once; it works for everything that needs uv

  2. Click this button to open VS Code

    Open in VS Code

    VS Code asks you to confirm; click Install

  3. Open the AI chat in VS Code in Agent mode

  4. Try it

    Use Uniswap Universal Router Decoder and tell me what you can do for me, then show me one thing

    ✓ If VS Code says it is using Uniswap Universal Router Decoder or shows a Uniswap Universal Router Decoder tool in the answer, you are connected

1 optional setting(s) (works without them)

The command above works without these. Add them only if you want to change something, following the maker’s description.

  • RPC_URL Ethereum RPC endpoint. Optional: only decode_transaction needs it.

Descriptions are as written by the maker.

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 →

JSON settings are under “For developers” below

Stuck? Ask people who use Uniswap Universal Router Decoder💬 Discussion →
For developers: Terminal commands and JSON settings

Installed on your computer

Claude Code

claude mcp add --scope user uniswap-universal-router-decoder -- uvx uniswap-universal-router-decoder

Claude Desktop (claude_desktop_config.json)

{
  "mcpServers": {
    "uniswap-universal-router-decoder": {
      "command": "uvx",
      "args": [
        "uniswap-universal-router-decoder"
      ]
    }
  }
}

Cursor (~/.cursor/mcp.json)

{
  "mcpServers": {
    "uniswap-universal-router-decoder": {
      "command": "uvx",
      "args": [
        "uniswap-universal-router-decoder"
      ]
    }
  }
}

VS Code (mcp.json)

{
  "servers": {
    "uniswap-universal-router-decoder": {
      "type": "stdio",
      "command": "uvx",
      "args": [
        "uniswap-universal-router-decoder"
      ]
    }
  }
}

Values you fill in

  • RPC_URL env
    Ethereum RPC endpoint. Optional: only decode_transaction needs it.

Descriptions are as written by the maker.

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

At a glance

Downloads per weeki
655/wk
Connection
Runs on your computer
Latest versioni
4.0.0
Published to registryi
Oct 29, 2026
Code last changedi
Nov 9, 2026
Maker
Elnaril
Packages
pypi: uniswap-universal-router-decoder
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.

Run on your computer in

ClaudeGooseLM StudioMsty StudioCherry StudioCursorVS Code + GitHub CopilotVisual StudioWindsurf (Devin Desktop)ZedKiroClineContinueJetBrains AI AssistantClaude CodeCodex CLIGemini CLIOpenCodenodecodeWarpLibreChatRaycast

All apps, with pros and cons →

Related guides

What it can do

Runs on your computer; the tool list appears in your AI app after you install it.

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 15, 2026

  • ✓ Pass

    Maker matches the repo

    The registry name was verified with the GitHub account Elnaril, which owns the repo

  • ✓ Pass

    Still maintained

    Code last changed 6 days ago

  • ✓ Pass

    Has a licence

    Uses MIT

  • – Not applicable

    Endpoint responds

    This one runs on your computer; there is no internet endpoint

  • – Not applicable

    Sign-in with OAuth

    Runs on your computer and uses local settings instead

  • … Not checked yet

    No hidden instructions in tool descriptions

    Runs on your computer; we can only read tool lists from internet endpoints

Published vulnerabilities (OSV.dev)

No entries on OSV.dev for uniswap-universal-router-decoder@4.0.0

Checks only this package version, not every dependency · checked Nov 15, 2026

What we check → · JSON

Makers: ask for a re-check or report wrong info

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.

Sign in to post

User reviews

No reviews yet

Sign in to write a review

Compared with others in Crypto & blockchaini

  • More stars than 99% of the other 1705 servers in this category
  • Published to the registry more recently than 75% of the other 1705 servers in this category
  • Basic checks equal to or better than 100% of the other 1705 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 Uniswap Universal Router Decoder safe?

It passed 3 of 3 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 on your computer. Your AI app starts it when needed, and data does not pass through the maker’s servers (unless it calls an online service itself).

Is it still maintained?

The GitHub repo last changed 6 days ago, and the latest version (4.0.0) reached the registry 17 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. You also need Python (uv) on your computer.

What can I use instead?

In the same category: DexSQL, PayRam, DexPaprika, Alchemy MCP Server, X402 List MCP

Similar alternatives

Same category, other makers, commands already checked. Official ones first, then by stars.

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

DexSQL

SQL for Android APK and DEX files: classes, methods, strings, references and smali.

by LSPosedGrowing★ 310Updated 28 days ago

Runs on your computer✓ lsposed.org

PayRam

Install, configure, operate and integrate self-hosted PayRam crypto payment gateways.

by PayRamGrowing★ 158Updated 39 days ago

Runs in the cloud✓ service owner · payram.com

DexPaprika

DEX and on-chain data: liquidity pools, token prices, swaps, and trading volume.

by coinpaprikaGrowing★ 120Updated 2 days ago

Runs in the cloud✓ service owner · dexpaprika.com

Alchemy MCP Server

Blockchain data across 100+ chains: token prices, NFTs, transfers, simulation, traces, Solana DAS

by alchemyplatformGrowing★ 88Updated 4 days ago

Runs in the cloud✓ service owner · alchemy.com

X402 List MCP

Find and vet x402 payment APIs before your agent pays one: uptime, price, on-chain volume.

by mcccsmEarly↓ 99/wk★ 18Updated 36 days ago

Computer or cloud✓ service owner · x402-list.com
  • DexSQL — Installs on your computer · No key needed
  • PayRam — Runs in the cloud, nothing to install · No key needed
  • DexPaprika — Runs in the cloud, nothing to install · No key needed
  • Alchemy MCP Server — Runs in the cloud, nothing to install · No key needed
  • X402 List MCP — Cloud or install on your computer · No key needed

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.

Uniswap Universal Router Decoder & Encoder

Many thanks to everyone who has ☕️ offered some coffees! ☕️

or ⭐ starred this project! ⭐

It is greatly appreciated! :)



Project Information
Code Quality

Release Notes

See the release notes page

v4.0.0 - breaking changes
  • Update COMMAND_TYPE_MASK to 0x7f to match UR
  • Add support for the PAY_PORTION_FULL_PRECISION command (0x07)
  • Add support for the BALANCE_CHECK_ERC20 command (0x0e)
  • Add support for the V3_POSITION_MANAGER_PERMIT command (0x11)
  • Add support for the V3_POSITION_MANAGER_CALL command (0x12)
  • Add support for the EXECUTE_SUB_PLAN command (0x21)
  • Add revert_on_fail to the encoder methods for the commands whose failure the UR can tolerate
  • Capture the bytes some callers append after the UR arguments as trailing_data, and re-append them when rebuilding the calldata, so a decoded call can be rebuilt byte-for-byte
  • Make the chained function builders public and expose the encoder & decoder modules
  • Reduce CI time
  • Add a publish.yml GitHub Actions workflow that automatically publishes the package to PyPI and the MCP Registry with OIDC Trusted Publishing
  • Agent-friendly changes:
  • Add Encoder.function_input() / AsyncEncoder.function_input() to rebuild the calldata from a decoded call
  • Add decoded_input_to_dict() and transaction_to_dict() to render the decoder output as JSON-friendly dicts
  • Add the ur-decode and ur-encode command line tools, including ur-encode v3-path and its encode_v3_path MCP counterpart
  • Add the ur-mcp MCP server (optional mcp extra) so AI agents can drive the codec, including encode_calldata to rebuild the calldata from a decoded call
  • Annotate the MCP tools as read-only so a host can auto-approve them, and give them human-readable titles
  • The command descriptions (ur-encode list / describe and the list_commands / describe_command MCP tools) now describe the decoded call format and its ABI parameters, instead of the encoder methods
  • Add the MCP Registry metadata (server.json) to make the ur-mcp server discoverable
  • Add AGENTS.md and llms.txt for AI agents, plus a mcp PyPI keyword
  • Add tests/test_version_consistency.py to keep the packaging version, server.json and the README mcp-name: marker in sync

Overview and Points of Attention

The object of this library is to decode & encode transactions sent to the Uniswap Universal Router (UR) on Ethereum Mainnet, though it would work on any compatible chain where the UR is deployed. See Version Mapping below. This Python SDK is based on, and intended to be used with web3.py

The target audience is Python developers who are familiar with the Ethereum blockchain concepts and web3.py, and how DEXes work. The same codec is also available without Python, through the ur-decode / ur-encode command line tools and the optional ur-mcp MCP server (see "Command line interface" and "MCP server" below): both print JSON, so shell scripts and AI agents can drive it too.

⚠ Before using this library, ensure you are familiar with general blockchain concepts. The Python API also expects web3.py knowledge in particular.

⚠ Not all UR functions supported by this SDK are available through the CLI or MCP tools: run ur-encode list and look for the "rebuildable" flag.

List of supported Uniswap Universal Router Functions
Command IdUniversal Router FunctionUnderlying Action - FunctionSupported
0x00 / 0V3_SWAP_EXACT_IN✅
0x01 / 1V3_SWAP_EXACT_OUT✅
0x02 / 2PERMIT2_TRANSFER_FROM✅
0x03 / 3PERMIT2_PERMIT_BATCH✅
0x04 / 4SWEEP✅
0x05 / 5TRANSFER✅
0x06 / 6PAY_PORTION✅
0x07 / 7PAY_PORTION_FULL_PRECISION✅
0x08 / 8V2_SWAP_EXACT_IN✅
0x09 / 9V2_SWAP_EXACT_OUT✅
0x0a / 10PERMIT2_PERMIT✅
0x0b / 11WRAP_ETH✅
0x0c / 12UNWRAP_WETH✅
0x0d / 13PERMIT2_TRANSFER_FROM_BATCH✅
0x0e / 14BALANCE_CHECK_ERC20✅
0x0f / 15placeholderN/A
0x10 / 16V4_SWAP✅
0x06 - SWAP_EXACT_IN_SINGLE✅
0x07 - SWAP_EXACT_IN✅
0x08 - SWAP_EXACT_OUT_SINGLE✅
0x09 - SWAP_EXACT_OUT✅
0x0b - SETTLE✅
0x0c - SETTLE_ALL✅
0x0e - TAKE✅
0x0f - TAKE_ALL✅
0x10 - TAKE_PORTION✅
0x11 / 17V3_POSITION_MANAGER_PERMIT✅
0x12 / 18V3_POSITION_MANAGER_CALL✅
0x13 / 19V4_INITIALIZE_POOL✅
0x14 / 20V4_POSITION_MANAGER_CALL✅
0x02 - MINT_POSITION✅
0x0b - SETTLE✅
0x0d - SETTLE_PAIR✅
0x0e - TAKE✅
0x11 - TAKE_PAIR✅
0x12 - CLOSE_CURRENCY✅
0x13 - CLEAR_OR_TAKE✅
0x14 - SWEEP✅
0x15 - WRAP✅
0x16 - UNWRAP✅
0x15 - 0x20placeholdersN/A
0x21 / 33EXECUTE_SUB_PLAN✅
0x22 - 0x3fplaceholdersN/A
0x40 / 64ACROSS_V4_DEPOSIT_V3❌

All the ✅ commands can be decoded and encoded. V4_SWAP, V4_POSITION_MANAGER_CALL and EXECUTE_SUB_PLAN can also be decoded, but they cannot be rebuilt from a decoded call (see "How to rebuild the calldata from a decoded call").

Version Mapping

Here is the mapping between the Universal Router versions and the SDK ones


Installation

A good practice is to use Python virtual environments, here is a tutorial.

The library can be pip installed from pypi.org as usual:

# update pip to latest version if needed

pip install -U pip

install the decoder from pypi.org

pip install uniswap-universal-router-decoder

To install it from source:

pip install .

or for contributors:

pip install -e '.[mc

Only the beginning is shown; read the rest in the repo