Developers

One API in. One webhook out.

Yesly sits between your system and your customer. You create the appointment; we get the answer and send it back. No templates to approve, no carriers to sign, no telephony to run.

Read the API reference Get sandbox access

REST + JSON
SDKs in 5 languages
Signed webhooks
Sandbox with test numbers
CSV import

Integration

Three steps. Two of them are ours.

01
Create the appointment
One POST with the customer, the slot and, if you like, your own metadata such as the order number. Create them one by one as your system schedules, or in bulk every morning.
POST /v1/appointments
02
We run the channel chain
WhatsApp first, SMS if there is no reply, a voice call if still nothing. Templates, numbers and carriers are ours. You do nothing.
whatsapp → sms → voice
03
Receive the answer
A signed webhook with confirmed, rescheduled or cancelled, the channel that got it, the new slot when there is one, and your metadata exactly as you sent it.
appointment.confirmed

Time to first confirmation: Minutes after your first POST
Typical integration: One developer, two to five days
Idempotency: By external_id, safe to retry
Webhook retries: Exponential backoff for 24 h

Escalation

The full flow, step by step.

Your system

Creates the appointment

Sent the day before the appointment

No reply in 2 h

SMS

Reaches any phone, no data needed

No reply in 2 h

Voice call

Natural voice, only when nothing else worked

No answer · flagged for your team

Answers

Answered

Confirmed

Webhook sent to you

Your system

Sends the appointment via API

Sent the day before the appointment

Answers → confirmed

No reply in 2 h

SMS

Reaches any phone, no data needed

Answers → confirmed

No reply in 2 h

Voice call

Natural voice, only when nothing else worked

Answered → confirmed

No answer · flagged for your team

Confirmed

Or rescheduled, or cancelled. Webhook to your system.

Integration

One API and webhooks. Live in days.

Create the appointment with one call. Get the answer back with another. No templates to get approved, no carriers to sign.

REST with JSON and API keys
SDKs for Node.js, Python, PHP, Java and .NET
Signed webhooks
Sandbox environment
CSV import if you have no API yet

Read the API reference

1 · Create the appointment

curl -X POST https://api.yesly.io/v1/appointments \
  -H "Authorization: Bearer ysk_live_…" \
  -H "Content-Type: application/json" \
  -d '{
    "external_id": "ORD-48213",
    "type": "delivery",
    "customer": { "name": "Martha", "phone": "+34612345678" },
    "slot": { "start": "2026-11-13T09:00:00+01:00", "end": "2026-11-13T11:00:00+01:00" },
    "metadata": { "order_id": "PV-18342", "route_id": "BIO-07" }
  }'

$ npm install @yesly/node

import Yesly from "@yesly/node";

const yesly = new Yesly(process.env.YESLY_API_KEY);

await yesly.appointments.create({
  external_id: "ORD-48213",
  type: "delivery",
  customer: { name: "Martha", phone: "+34612345678" },
  slot: { start: "2026-11-13T09:00:00+01:00", end: "2026-11-13T11:00:00+01:00" },
  metadata: { order_id: "PV-18342", route_id: "BIO-07" },
});

$ pip install yesly

import os
from yesly import Yesly

yesly = Yesly(api_key=os.environ["YESLY_API_KEY"])

yesly.appointments.create(
    external_id="ORD-48213",
    type="delivery",
    customer={"name": "Martha", "phone": "+34612345678"},
    slot={"start": "2026-11-13T09:00:00+01:00", "end": "2026-11-13T11:00:00+01:00"},
    metadata={"order_id": "PV-18342", "route_id": "BIO-07"},
)

$ composer require yesly/yesly-php

$yesly = new \Yesly\Client(getenv('YESLY_API_KEY'));

$yesly->appointments->create([
    'external_id' => 'ORD-48213',
    'type' => 'delivery',
    'customer' => ['name' => 'Martha', 'phone' => '+34612345678'],
    'slot' => ['start' => '2026-11-13T09:00:00+01:00', 'end' => '2026-11-13T11:00:00+01:00'],
    'metadata' => ['order_id' => 'PV-18342', 'route_id' => 'BIO-07'],
]);

implementation("io.yesly:yesly-java:1.+")

Yesly yesly = new Yesly(System.getenv("YESLY_API_KEY"));

yesly.appointments().create(AppointmentCreateParams.builder()
    .externalId("ORD-48213")
    .type("delivery")
    .customer("Martha", "+34612345678")
    .slot("2026-11-13T09:00:00+01:00", "2026-11-13T11:00:00+01:00")
    .putMetadata("order_id", "PV-18342")
    .putMetadata("route_id", "BIO-07")
    .build());

$ dotnet add package Yesly

var yesly = new YeslyClient(Environment.GetEnvironmentVariable("YESLY_API_KEY"));

await yesly.Appointments.CreateAsync(new AppointmentCreateOptions
{
    ExternalId = "ORD-48213",
    Type = "delivery",
    Customer = new() { Name = "Martha", Phone = "+34612345678" },
    Slot = new() { Start = "2026-11-13T09:00:00+01:00", End = "2026-11-13T11:00:00+01:00" },
    Metadata = new() { ["order_id"] = "PV-18342", ["route_id"] = "BIO-07" },
});

2 · Receive the answer by webhook 200

{
  "id": "evt_5Hq1Kd",
  "type": "appointment.confirmed",
  "data": {
    "appointment": {
      "external_id": "ORD-48213",
      "status": "confirmed",
      "answer": { "channel": "whatsapp", "at": "2026-11-12T10:04:12+01:00" },
      "metadata": { "order_id": "PV-18342", "route_id": "BIO-07" }
    }
  }
}

Trust

We talk to your customers. We take that seriously.

Data stays in the EU
Processed and stored in European data centres.
GDPR, DPA included
We act as data processor, with a DPA for every customer.
Built on AWS
High availability, automatic backups, ISO 27001 and ENS.
Encrypted, signed webhooks
TLS everywhere, managed keys, every webhook signed.
Never at night
Never more than agreed. Your customer opts out in one message.
Nothing falls through
Every unanswered appointment is flagged for your team.

One API in. One webhook out.

Three steps. Two of them are ours.

Create the appointment

We run the channel chain

Receive the answer

The full flow, step by step.

One API and webhooks. Live in days.

We talk to your customers. We take that seriously.

Data stays in the EU

GDPR, DPA included

Built on AWS

Encrypted, signed webhooks

Never at night

Nothing falls through