n8n Custom Node — NPM Package Skill

Core Mental Model

Every n8n node follows one pattern:

getInputData()  →  loop items  →  do stuff  →  push to returnData  →  return [returnData]

Two file types do all the work:

• Node file (nodes/MyNode/MyNode.node.ts) — UI fields + execute logic
• Credential file (credentials/MyApi.credentials.ts) — auth definition

Everything else is project plumbing.

Project Structure

n8n-nodes-yourservice/
├── package.json              ← CRITICAL: must have n8n section + correct keyword
├── tsconfig.json
├── .eslintrc.js
├── gulpfile.js               ← copies SVG icons to dist/
├── index.js                  ← optional explicit entry point
├── nodes/
│   └── YourService/
│       ├── YourService.node.ts
│       ├── YourService.node.json   ← optional: codex metadata
│       └── yourservice.svg
├── credentials/
│   └── YourServiceApi.credentials.ts
└── dist/                     ← compiled output (never edit manually)

What to Read and When

This skill has focused reference files. Load only what you need:

Node Types (pick one)

Credentials (pick what matches your auth)

Concepts (load when the topic comes up)

Project Setup & Publishing

Quick-Start Pattern (copy this first)

// nodes/YourService/YourService.node.ts
import {
  IExecuteFunctions,
  INodeExecutionData,
  INodeType,
  INodeTypeDescription,
  NodeOperationError,
} from 'n8n-workflow';

export class YourService implements INodeType {
  description: INodeTypeDescription = {
    displayName: 'Your Service',
    name: 'yourService',
    icon: 'file:yourservice.svg',
    group: ['transform'],
    version: 1,
    description: 'Interact with Your Service API',
    defaults: { name: 'Your Service' },
    inputs: ['main'],
    outputs: ['main'],
    credentials: [{ name: 'yourServiceApi', required: true }],
    properties: [
      {
        displayName: 'Endpoint',
        name: 'endpoint',
        type: 'string',
        default: '/users',
        required: true,
      },
    ],
  };

  async execute(this: IExecuteFunctions): Promise<INodeExecutionData[][]> {
    const items = this.getInputData();
    const returnData: INodeExecutionData[] = [];
    const credentials = await this.getCredentials('yourServiceApi');

    for (let i = 0; i < items.length; i++) {
      try {
        const endpoint = this.getNodeParameter('endpoint', i) as string;

        const response = await this.helpers.httpRequest({
          method: 'GET',
          url: `https://api.yourservice.com${endpoint}`,
          headers: {
            Authorization: `Bearer ${credentials.apiToken}`,
          },
        });

        returnData.push({ json: response, pairedItem: { item: i } });

      } catch (error) {
        if (this.continueOnFail()) {
          returnData.push({ json: { error: error.message }, pairedItem: { item: i } });
          continue;
        }
        throw new NodeOperationError(this.getNode(), error, { itemIndex: i });
      }
    }

    return [returnData];
  }
}

Essential APIs Cheat Sheet

// Input
const items = this.getInputData();

// Parameters
this.getNodeParameter('name', i) as string
this.getNodeParameter('count', i, 0) as number
this.getNodeParameter('options', i, {}) as IDataObject

// Credentials
const creds = await this.getCredentials('myCredentialName');

// HTTP
await this.helpers.httpRequest({ method, url, headers, qs, body })

// Error handling
this.continueOnFail()
throw new NodeOperationError(this.getNode(), message, { itemIndex: i })
throw new NodeApiError(this.getNode(), error)   // for API-level HTTP errors

// Output
returnData.push({ json: data, pairedItem: { item: i } })
return [returnData];

Pre-Publish Checklist

• [ ] keywords in package.json includes "n8n-community-node-package"
• [ ] n8n.nodes and n8n.credentials arrays point to dist/ .js paths
• [ ] Node name is camelCase; displayName is human-readable
• [ ] Credential name exactly matches string passed to getCredentials('...')
• [ ] Every returnData.push() includes pairedItem: { item: i }
• [ ] continueOnFail() is handled in all try/catch blocks
• [ ] SVG icon exists in nodes/YourService/ and referenced as 'file:yourservice.svg'
• [ ] npm run build succeeds (no TypeScript errors)
• [ ] npm run lint passes (required for community submission)
• [ ] Tested locally via npm link
• [ ] Version bumped in package.json before publish