---
title: Overview
description: The Notecard API is a collection of requests for interfacing with a Blues Notecard to build an IoT application with Cellular, Satellite, LoRa, or WiFi connectivity.
source_url: https://dev.blues.io/notecard/notecard-walkthrough/overview/
canonical_url: https://dev.blues.io/notecard/notecard-walkthrough/overview/
markdown_url: https://dev.blues.io/notecard/notecard-walkthrough/overview.md
---

# Notecard

**Notecard** is a wireless IoT device that connects physical devices to cloud applications via low-power cellular, satellite, WiFi, or LoRa. Data is queued in onboard flash and synced with the secure cloud service, **Notehub**, at user-defined intervals. Notehub can then securely route this data to any cloud application.

Rather than requiring the use of cryptic AT commands or manual byte manipulation, the Notecard API consists of [JSON](https://dev.blues.io/api-reference/glossary.md#json) requests and responses. The firmware running on the Notecard implements a synchronous protocol that watches for newline-terminated (`\n` or `\r\n`) JSON requests and returns a newline-terminated (`\r\n`) JSON-formatted response. All interaction between the Notecard and a host microcontroller or microprocessor occurs using this JSON protocol.

For development and exploration purposes, you can interact with the Notecard through a USB Serial connection to a host computer. Examples in this guide can be run directly against a USB-connected Notecard using the [In-Browser Terminal](https://dev.blues.io/terminal/) or from the [Notecard CLI](https://dev.blues.io/tools-and-sdks/notecard-cli.md).

> **Tip:**
>
> **Just getting started?**
>
> [Watch a guided demo](https://youtu.be/mbWQri93oYU) and learn how to get started with wireless connectivity at Blues.
>
> **Looking for firmware libraries?**
>
> Visit the [libraries page](https://dev.blues.io/tools-and-sdks.md) for an SDK for your preferred language.

## The Notecard & Notehub

It's important to understand a few key concepts of the Blues ecosystem:

- **Notecard** is a device-to-cloud data pump that reduces the complexity of building connected solutions with a secure, reliable [cellular](https://dev.blues.io/cellular-iot/), [satellite](https://dev.blues.io/satellite-ntn-iot/), [WiFi](https://dev.blues.io/wifi-iot/), or [LoRa](https://dev.blues.io/lora-lorawan-iot/) connection. It's a System-on-Module (SOM) that's ready for embedding into any product. Notecard stores your data locally in onboard flash and syncs it with the cloud on a schedule you choose, so your application keeps collecting through connectivity gaps.

- **Notecarriers** are development boards that help you get started quickly with the Notecard. There are a [variety of Notecarriers](https://shop.blues.com/collections/notecarrier?utm_source=dev-blues\&utm_medium=web\&utm_campaign=store-link) designed to fit different needs, and many include onboard Cellular and GPS antennas, as well as a USB port for Serial access to the Notecard.

- **Notehub** is the secure cloud service the Notecard uses as a proxy to send and receive data. Notehub also provides a console for fleet management and secure connectors for [routing data to 3rd party cloud applications](https://dev.blues.io/guides-and-tutorials/routing-data-to-cloud.md).

- A **Note** is a JSON object containing developer-provided content. A Note is the primary means of sending data to/from a Notecard.

Notecard and Notehub work together to provide *bidirectional* wireless communication capabilities, both *outbound* (from your microcontroller or single-board computer to the cloud):

[Video: animation of outbound communication from notecard to notehub to cloud](https://dev.blues.io/images/reference/notecard-api/outbound.mp4)

And *inbound* (from the cloud to your microcontroller or single-board computer):

[Video: animation of inbound communication from cloud to notehub to notecard](https://dev.blues.io/images/reference/notecard-api/inbound.mp4)

[Notecard Requests & Responses](https://dev.blues.io/notecard/notecard-walkthrough/notecard-requests-and-responses.md "Notecard Requests & Responses")