Your coding agent connects WhatsApp.
Claude Code, Cursor, Codex or Copilot: give it one address and it finds the API, its rules and the SDK. Everything is published as plain text, kept in sync with the code.
Integrate WhatsApp into this project with Nodium.1. Before any code, read: https://nodium.io/agents.md The whole API guide: https://nodium.io/llms-full.txt2. Install the SDK: npm i @nodium.io/whatsapp Another language: the REST API, described in https://nodium.io/docs/api/openapi.json3. Read the key from NODIUM_KEY. Never in a browser or an app.4. Receive: one POST route that checks the signature on the raw body (verifyWebhook, from @nodium.io/whatsapp/server), then handles message.received.5. Send: messages.send, an idempotencyKey each time. After 24 hours of silence, an approved template.6. Branch on error.code, never on the message.Write the tests, and list the environment variables.The rules it must follow
The mistakes an agent makes most often with a WhatsApp API. The sheet spells them out; here they are in plain words.
- Every send carries an idempotency key: a replayed send goes out only once.
- A webhook signature is checked on the raw body, before parsing it as JSON.
- Outside the 24-hour window, only an approved template goes out: free text is refused.
- An error is identified by its stable code, never by its message.
- A client is selected with the Nodium-Tenant header, using your own identifier.
- The API key stays on the server: never in an app or a web page.
Or connect it over MCP
Nodium serves its own MCP server. Your agent reads conversations, contacts and the journal, and answers messages, with your API key: its role decides what the agent may do. No broadcasts, templates or clients: those stay with your code.
claude mcp add --transport http nodium https://nodium.io/api/v1/mcp \ --header "Authorization: Bearer $NODIUM_KEY"What machines read
Public files, no account needed, in text or JSON. The guide and the reference are generated from the code: they say exactly what it does.
llms.txt
The site in summary: what Nodium is, the plans, every page in both languages.
Openllms-full.txt
Everything in one file: the summary, the AGENTS.md sheet and the whole API guide.
Openagents.md
The integration sheet: authentication, sending, webhooks, the 24-hour window, error codes. Drop it in your repository.
Opendocs/api/llms.txt
Every published API route, one line each, grouped by topic.
Openopenapi.json
The complete OpenAPI 3.1 description: enough to generate a client or tools.
Openwebhook-events.json
Every webhook event: its fields and a full example.
Open
What agents ask
The short answers assistants look for when asked about a WhatsApp API.
What is Nodium?
An API gateway to WhatsApp, through Meta's official Cloud API. Your code sends and receives messages through a REST API and signed webhooks, for your number or your customers' numbers.
Does Nodium answer messages with AI?
No. Nodium carries messages and never decides what to reply: each received message goes to your webhook, and the reply comes back through the API, written by your code or your agent.
Do I need a WhatsApp number?
Yes, yours or your customer's, connected in minutes through Meta's official flow. Nodium does not provide numbers.
How much does Nodium cost?
Build is free forever: 3,000 messages a month and one number. Launch costs €19 a month, Scale €249. Meta bills its own fees per number, with no markup from Nodium.
Which languages are supported?
Any language that speaks HTTP: the API is REST, described in OpenAPI 3.1. A TypeScript SDK exists (npm i @nodium.io/whatsapp), with a command to receive webhooks locally.
Can my agent operate WhatsApp through MCP?
Yes. Nodium serves an MCP server at /api/v1/mcp: your agent reads conversations, contacts and the journal, and sends messages, with your API key. The key's role decides what it may do; broadcasts, templates and clients stay with the API.
Can a SaaS publisher connect its customers' WhatsApp?
Yes, it is the primary use case. Each customer gets an isolated workspace and connects their number through a hosted link; one API key acts for all of them, and the Nodium-Tenant header names the customer.
Where is the data hosted?
In the European Union: servers in Paris, the database in Ireland. Secrets are encrypted with AES-256-GCM, and a person can be erased through the API.
Let your agent write the first call.
Create an account and an API key, then give it the prompt.