runtime

Self-hosted MCP server: 26 deterministic dev, security, and EVM tools.

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What it can do

    What data it sees

    Do you need an account

    No: the server works without sign-in

    Self-hosted MCP server: 26 deterministic dev, security, and EVM tools.

    How to connect

    How to connect runtime to Claude

    The server address to paste into Claude settings:

    https://mcp.formatho.com/mcp

    1. Open Claude (claude.ai or the desktop app).
    2. Go to Settings → Connectors.
    3. Click Add custom connector.
    4. Paste the server address copied below into Remote MCP server URL and click Add.
    5. In a chat, click + → Connectors and switch the new connector on.

    Custom connectors are available on Free, Pro, Max, Team and Enterprise plans (Free is limited to one). On Team and Enterprise an organization Owner adds the connector first under Organization settings → Connectors.

    Authorization

    After you click Add, a sign-in window for the service opens. Sign in with your own account and approve access. Claude never sees your password.

    How to connect runtime to ChatGPT

    The server address to paste into ChatGPT settings:

    https://mcp.formatho.com/mcp

    1. Open ChatGPT in a browser (chatgpt.com). A Plus, Pro, Business, Enterprise or Edu plan is required.
    2. Turn on developer mode once: Settings → Apps → Advanced settings → Developer mode.
    3. Open Settings → Connectors and click Create.
    4. Fill in the form: Name (anything), Description (one line about what the service does), MCP server URL (copy it below).
    5. Under Authentication choose OAuth if the service requires sign-in, otherwise None. Click Create.
    6. In a new chat open + → Apps/Connectors and enable the connector.

    OpenAI has renamed this section before (Connectors → Apps/Plugins). If the label differs, search settings for "developer mode". On Business/Enterprise workspaces an admin must allow custom connectors first.

    Authorization

    On first use ChatGPT opens the service's sign-in window. Sign in and approve access.

    How to connect runtime to Cursor

    The server address to paste into Cursor settings:

    https://mcp.formatho.com/mcp

    Fastest: click Open in Cursor below and confirm the prompt.

    Manually:

    1. In Cursor open Settings → Cursor Settings → MCP and click Add new global MCP server.
    2. Paste the JSON copied below into ~/.cursor/mcp.json (per project: .cursor/mcp.json in the repo root).
    3. Save the file. The server appears in the MCP list; authorize it there if asked.

    Authorization

    If the service needs sign-in, an authorize button appears next to the server in the MCP list.

    Server tool list (26)

    Raw names from tools/list. Only developers need these.

    json.formatValidate and pretty-print JSON with a configurable indent level. [data · v1.0.0 · deterministic: true · permissions: none]
    json.minifyValidate JSON and strip all insignificant whitespace. [data · v1.0.0 · deterministic: true · permissions: none]
    json.validateValidate JSON and report the parse error position if invalid. [data · v1.0.0 · deterministic: true · permissions: none]
    base64.encodeBase64-encode text (standard alphabet). [data · v1.0.0 · deterministic: true · permissions: none]
    base64.decodeBase64-decode to text. [data · v1.0.0 · deterministic: true · permissions: none]
    url.encodePercent-encode text (component encoding). [network · v1.0.0 · deterministic: true · permissions: none]
    url.decodeDecode percent-encoded text. [network · v1.0.0 · deterministic: true · permissions: none]
    slug.generateConvert text to a URL-safe kebab-case slug. [dev · v1.0.0 · deterministic: true · permissions: none]
    hash.textHash text with md5/sha1/sha256/sha384/sha512 (hex output). MD5/SHA1 are for compatibility checks only, not security. [security · v1.0.0 · deterministic: true · permissions: none]
    uuid.v4Generate random UUID v4 values. [security · v1.0.0 · deterministic: false · permissions: none]
    random.stringGenerate a cryptographically random alphanumeric string. [security · v1.0.0 · deterministic: false · permissions: none]
    jwt.decodeDecode a JWT (JWS compact serialization) header and claims WITHOUT verifying the signature. Reports expiry status from the exp claim. [security · v1.0.0 · deterministic: true · permissions: none]
    evm.keccak256Keccak-256 (Ethereum flavor, NOT NIST SHA3-256) of arbitrary hex or text. [web3 · v1.0.0 · deterministic: true · permissions: none]
    evm.function_selectorCompute the 4-byte function selector from a canonical signature, with reverse lookup against common signatures. [web3 · v1.0.0 · deterministic: true · permissions: none]
    evm.create2_addressCompute the deterministic CREATE2 address: keccak256(0xff ‖ factory ‖ salt ‖ initCodeHash)[12:]. [web3 · v1.0.0 · deterministic: true · permissions: none]
    evm.storage_slotCompute Solidity storage slots: simple variables, mapping values (keccak(key ‖ p)), and dynamic array elements (keccak(p) + index). [web3 · v1.0.0 · deterministic: true · permissions: none]
    evm.decode_calldataExtract the 4-byte selector from raw calldata, match it against common signatures, and decode static (word-based) arguments: address, uint256, int256, bytes32, bool. [web3 · v1.0.0 · deterministic: true · permissions: none]
    evm.v4_hook_permissionsUniswap v4 hook permissions: compute the 14-bit permission field from hook-call names, or decode the field from a hook address (bits live in the LOW 14 bits: address & 0x3FFF). [web3 · v1.0.0 · deterministic: true · permissions: none]
    erc4626.mathExact EIP-4626 vault math in BigInt: convert assets to shares (round down) and shares to assets (round down), with optional virtual offsets. [defi · v1.0.0 · deterministic: true · permissions: none]
    timestamp.convertConvert Unix seconds/milliseconds to ISO 8601 (UTC) and back. [dev · v1.0.0 · deterministic: true · permissions: none]
    regex.testTest a regular expression against text: match result plus all capture groups. [dev · v1.0.0 · deterministic: true · permissions: none]
    case.convertConvert an identifier between camelCase, snake_case, kebab-case, CONSTANT_CASE, and Title Case. [dev · v1.0.0 · deterministic: true · permissions: none]
    hex.encodeEncode text to hex, or decode hex (with or without 0x) to text. [data · v1.0.0 · deterministic: true · permissions: none]
    evm.checksum_addressEIP-55 checksum an Ethereum address, or verify a checksummed one. [web3 · v1.0.0 · deterministic: true · permissions: none]
    evm.unit_convertConvert EVM amounts between wei, gwei, and ether with exact BigInt math. [web3 · v1.0.0 · deterministic: true · permissions: none]
    formatho.registryList every registered Formatho tool with version, category, deterministic flag, permissions, and Formatho Verified status. [meta · v1.0.0 · deterministic: true · permissions: none]