Key, bridge, phone. Then a message.
Run these in order. Your first bridge is free for 7 days with a card on file, nothing charged until the trial ends.
Create an API key at Dashboard → API keys. It starts with sk_ and is shown once, so copy it now. Every call below sends it as Authorization: Bearer $WA_API_KEY.
customer_ref = sandbox. Skip steps 2 and 3, use sandbox wherever a customer_ref appears below, and send to 15550001234, a fake contact who replies within seconds. Events show on your dashboard.gem install sinatra
export WA_API_KEY="sk_..."
Your first bridge is created from the dashboard: one click connects a number and starts the 7-day free trial (card on file, $0 today). Every API call below can address it as /api/instances/default/…: default always means your first bridge, so no name goes in the URL. The call here is how you add more bridges to the subscription.
customer_ref is your internal identifier (user ID, slug, anything you control). webhook_url is optional: leave it out to use the hosted inbox and read events on the dashboard, change it any time with PATCH.
Store the webhook_secret that comes back. It signs every webhook the bridge sends you.
402 no_subscription: connect a number in the dashboard first.require 'net/http'
require 'json'
API_KEY = ENV['WA_API_KEY']
BASE = 'https://wabridges.com/api'
def wa_post(path, body)
uri = URI("#{BASE}#{path}")
req = Net::HTTP::Post.new(uri)
req['Authorization'] = "Bearer #{API_KEY}"
req['Content-Type'] = 'application/json'
req.body = body.to_json
res = Net::HTTP.start(uri.host, uri.port, use_ssl: true) { |h| h.request(req) }
JSON.parse(res.body)
end
bridge = wa_post('/instances', {
customer_ref: 'user-123',
webhook_url: 'https://yourbackend.com/hook'
})
pp bridge
{"id": "7d09aa9c-…", "customer_ref": "user-123", "state": "running", "created_at": 1777180605, "webhook_secret": "whs_…", "webhook_url": "https://…/hook"}
You need the phone in hand for this step. Request a pairing code, open WhatsApp on the phone, go to Linked Devices → Link a device → Link with phone number, then enter the code. Any number works, personal, VoIP, or a spare SIM. No phone? Use sandbox.
Once paired, the bridge fires a connected webhook event. Poll /proxy/status or wait for the event.
result = wa_post('/instances/user-123/proxy/pair', { phone: '15550001234' })
puts "Enter this code on the phone: #{result['code']}"
{"code": "ABCD-EFGH"}
Add an Idempotency-Key: <unique-per-message> header in production so a timeout plus retry can never double-send. See Idempotency.
A bridge that sat for a few hours with no phone linked is paused to save resources. The first call after that returns 503 bridge_starting with a Retry-After header. Wait those seconds and retry once.
msg = wa_post('/instances/user-123/proxy/send/text', {
chat: '15559876543',
body: 'Hello from the API!'
})
puts msg['message_id']
{"message_id": "ACE41E...", "timestamp": 1777180605}
Inbound messages and events are delivered by POST to your webhook_url. Return 200 immediately and do the work afterwards.
The webhook guide has every event type and field, plus signature verification.
require 'sinatra'
require 'json'
post '/hook' do
payload = JSON.parse(request.body.read)
status 200
if payload['event'] == 'message' && !payload['from_me']
puts "#{payload['name']}: #{payload['body']}"
# reply with wa_post(...)
end
''
end
Next
Everything the quickstart skipped: media, polls, contacts, presence, and every webhook payload.