devtoolkit-mcp

26 developer utilities as an MCP server for AI-assisted workflows. JSON repair, SQL formatting, hashing, encoding, UUID generation, regex testing, CSV transforms, subnet calculation, diagram generation, and more.

No API keys. No network requests. Everything runs locally.

By Coding4Pizza

Quick Start

npx -y devtoolkit-mcp

Configuration

Claude Desktop

Add to ~/Library/Application Support/Claude/claude_desktop_config.json (macOS) or %APPDATA%\Claude\claude_desktop_config.json (Windows):

{
  "mcpServers": {
    "devtoolkit": {
      "command": "npx",
      "args": ["-y", "devtoolkit-mcp"]
    }
  }
}

Claude Code (CLI & VSCode Extension)

Add globally (available in all projects):

claude mcp add -s user devtoolkit -- npx -y devtoolkit-mcp

Or add for current project only:

claude mcp add devtoolkit -- npx -y devtoolkit-mcp

Note: Do NOT manually edit ~/.claude/.mcp.json — use claude mcp add to register servers correctly.

Cursor

Add to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "devtoolkit": {
      "command": "npx",
      "args": ["-y", "devtoolkit-mcp"]
    }
  }
}

VS Code (Copilot)

Add to .vscode/mcp.json in your project:

{
  "servers": {
    "devtoolkit": {
      "type": "stdio",
      "command": "npx",
      "args": ["-y", "devtoolkit-mcp"]
    }
  }
}

Windsurf

Add to ~/.codeium/windsurf/mcp_config.json:

{
  "mcpServers": {
    "devtoolkit": {
      "command": "npx",
      "args": ["-y", "devtoolkit-mcp"]
    }
  }
}

Available Tools (26)

Data Transform

| Tool | Description | |------|-------------| | repair_json | Fix malformed JSON — missing quotes, trailing commas, single quotes, comments | | format_sql | Format or minify SQL with 18+ dialect support | | format_list | Convert lists to SQL IN clause, VALUES, UNION, JSON array, CSV | | clean_list | Deduplicate, sort, trim, filter lists | | generate_mock_data | Generate fake data with 63+ field types via Faker.js (JSON/CSV/SQL) | | csv_transform | Parse, filter, sort, aggregate, convert CSV data | | yaml_json | Convert between YAML and JSON | | json_to_types | Convert JSON to TypeScript interfaces, Zod schemas, or JSON Schema | | generate_diagram | Generate Mermaid flowcharts and sequence diagrams from plain English descriptions |

Decode & Parse

| Tool | Description | |------|-------------| | decode_jwt | Decode JWT tokens — header, payload, expiration status | | parse_cron | Parse cron expressions — human-readable description + next run times | | convert_epoch | Convert between epoch timestamps and human dates | | convert_color | Convert colors (HEX/RGB/HSL/OKLCH) with WCAG contrast grades | | url_parse | Parse URLs into components, manipulate query parameters | | http_status | Look up HTTP status codes, headers, and MIME types with RFC references |

Crypto & Random

| Tool | Description | |------|-------------| | hash_text | Compute MD5, SHA-1, SHA-256, SHA-512 hashes and HMAC | | encode_decode | Encode/decode Base64, URL, HTML entities, Unicode escapes | | uuid_generate | Generate UUID v4, v7, NanoID, or ULID with true crypto randomness | | password_generate | Generate crypto-random passwords or passphrases with entropy estimate |

Dev Utilities

| Tool | Description | |------|-------------| | regex_test | Test regex patterns — matches, captures, named groups, replace | | number_base_convert | Convert between decimal, hex, binary, octal (BigInt support) | | diff_text | Line-by-line text diff using LCS algorithm | | string_case | Convert between camelCase, snake_case, kebab-case, PascalCase, CONSTANT_CASE, and more | | ip_subnet | IPv4 subnet calculator — CIDR, masks, host range, membership check | | timestamp_calc | Date math — add/subtract durations, diff between dates, timezone conversion |

Smart Detection

| Tool | Description | |------|-------------| | detect_content | Auto-detect content type (JSON, SQL, JWT, cron, etc.) with confidence score |

Examples

Just ask your AI assistant in natural language:

Hash "hello world" with SHA-256

Decode this JWT: eyJhbGciOiJIUzI1NiIs...

Convert 0xFF3A to binary

Test regex (\d{4})-(\d{2})-(\d{2}) against "2024-03-15"

Generate 5 UUID v7

What is 2024-01-15 + 90 days?

Calculate subnet for 192.168.1.0/24

Convert getUserHTTPResponse to snake_case

Convert this JSON to TypeScript: {"id": 1, "name": "John", "tags": ["admin"]}

Generate 20 mock users with id, name, email, salary as CSV, then filter salary > 60000

Draw diagram: User sends request to API Gateway, forwards to Auth Service, queries Postgres

Why MCP Tools vs Native AI?

These tools provide capabilities that AI models cannot do natively:

| Capability | AI Native | MCP Tool | |-----------|-----------|----------| | Compute SHA-256 hash | Cannot | Exact | | Generate true random UUIDs | Cannot | Crypto-random | | Base64 encode/decode | Often wrong | Exact | | Regex matching with captures | Often wrong | JS RegExp engine | | Subnet math (CIDR, masks) | Often wrong | Bit-level exact | | Date arithmetic | Often wrong | Millisecond exact | | CSV parsing (quoted fields) | Approximates | RFC-compliant | | Line-by-line diff | Misses changes | LCS algorithm | | Diagram generation | Approximates syntax | Valid Mermaid output |

Requirements

• Node.js >= 18

License

MIT

Links

• Website: coding4pizza.com
• Source: github.com/emtyty/devtool
• Issues: github.com/emtyty/devtool/issues