ESP32 OTA Updates: A Complete Guide to ArduinoOTA and ElegantOTA Firmware Upgrades

Dec 15th,2025

ESP32 OTA is a game-changer when it comes to updating firmware on a microcontroller. Traditionally, this means reaching for a USB cable, plugging into the board, and flashing the code manually. That works fine on your workbench, but once a device is installed in a ceiling, inside an enclosure, or deployed across several locations, physical access becomes a problem. Over-the-Air (OTA) updates solve this by allowing the device to receive new firmware through Wi-Fi—no cables, no disassembly, no downtime.
OTA is especially valuable on the ESP32, a board commonly used in IoT projects, smart home devices, and small-scale deployments. With OTA in place, With an ESP32 remote update system in place, you can push improvements, fix bugs, or roll out new features without touching the hardware.or roll out new features without touching the hardware. This greatly improves maintainability and makes large networks of ESP32s far easier to support.

What Is OTA Updating?

ESP32 over-the-air update (OTA) is the process of sending new firmware to a microcontroller wirelessly, eliminating the need for physical access.Instead of flashing code through USB, the firmware is uploaded through Wi-Fi using a web interface, a tool built into the IDE, or a custom update workflow.

For ESP32 projects, OTA offers three major benefits: 
✓ No USB cable required: You only need USB for the first flash. After that, updates can be delivered remotely. 
✓ Remote maintenance: OTA is ideal when the board is mounted somewhere inconvenient or inside a sealed box. 
✓ Better scalability: When you have multiple ESP32s deployed, OTA avoids physically visiting each device.

How ESP32 OTA Works (Simple Explanation)

The ESP32 stores firmware in flash memory. A small bootloader decides which section of memory contains the current application and loads it, similar to the initialization process explained in our ESP32 tutorial.When OTA is enabled, the flash is divided into two application partitions: app0 and app1.
Volumio
Here’s why this matters:
• The ESP32 always runs from one of the partitions.
• When you upload new firmware, the device writes it to the other partition.
•Once the upload is complete and verified, the bootloader switches to the new partition on the next reboot.
This two-partition design ensures safety, offering a fallback mechanism during an ESP32 firmware update. If something goes wrong during the update—power loss, Wi-Fi drop, corrupted file—the ESP32 still has the older firmware on the inactive partition and can fall back to it. Without dual partitions, a failed OTA update could brick the device.

Preparing the ESP32 for OTA

Before using OTA, a few conditions must be in place:
Libraries
• For ArduinoOTA, the core ESP32 Arduino package already includes the necessary headers.
• For ElegantOTA, you install a lightweight library that adds a web interface.
Network Requirements
• The ESP32 needs a stable Wi-Fi connection.
• The computer uploading the firmware must be on the same local network for ArduinoOTA, following the same network configuration principles in our ESP32-CAM setup guide.
• For ElegantOTA, any device on the network with a browser can access the update page.

Method 1: ArduinoOTA

When working with ESP32 OTA, ArduinoOTA is the simplest implementation, especially for developers using the Arduino IDE.It integrates directly with the Arduino IDE and allows you to upload firmware wirelessly as if you were flashing through USB.
When to Use It
• You’re developing locally and want to update a single ESP32 quickly.
• You prefer working inside the Arduino IDE.
• The ESP32 and your PC share the same Wi-Fi network.
Setup Steps
1. Open a BasicOTA example.

2. Connect the ESP32 to Wi-Fi.

3. Add OTA event handlers (start, end, progress, error).
4. Call ArduinoOTA.begin() in setup().
5. Add ArduinoOTA.handle() inside loop().
After the first wired upload, the Arduino IDE will show the ESP32 as a network port. Selecting this port allows you to upload over Wi-Fi with no extra steps, following the same ease-of-use principles highlighted in our Raspberry Pi OS setup guide.

Uploading

In the IDE, choose the board as usual, but in the Port menu, select the device listed under network ports. Flash the code, wait for the transfer to finish, and the ESP32 will reboot into the updated firmware.

Method 2: ElegantOTA (Web Interface OTA)

ElegantOTA is another powerful ESP32 OTA method that takes a different approach. Instead of relying on the IDE, it provides a web interface that lets you upload firmware using a browser. It’s clean, simple, and accessible from any phone or computer.
Why ElegantOTA Is More User-Friendly
• You don’t need the Arduino IDE.
• Anyone on the network can update the device through a webpage.
• It includes a progress bar and clear status messages.
• Ideal for field technicians or non-programmers.
Setup Steps
1. Install the ElegantOTA library.

2. Open a Demo example and upload it.
3. Open the page by typing the ESP32’s IP address in your browser.
Uploading Through the Browser
Once you access http://<device-ip>/update, you’ll see an upload form, similar to the interface described in this ESP32 OTA reference.Select your compiled .bin file and start the update. The page shows live progress and reboots automatically when done.

ArduinoOTA vs ElegantOTA (Quick Comparison)

If you mainly code in Arduino IDE, ArduinoOTA is convenient. If you expect other people to update the device or need a more polished interface, ElegantOTA is the better choice.

OTA Security Basics

ESP32 OTA security is critical, as the update process, while powerful, can become a vulnerability if left unprotected.Anyone able to reach the update interface could upload malicious firmware.
Secure Your OTA Process
• Password-protect ArduinoOTA: A simple password can block unwanted uploads.

• Use Basic Authentication with ElegantOTA: You can require a username and password on the update page.
• Limit network access: Prefer private networks, VPNs, or firewall rules.
• Never expose OTA ports directly to the public internet.

Best Practices for Reliable OTA

✓ Stable Wi-Fi
Make sure the ESP32 has a strong signal, as weak Wi-Fi is a common cause of failed OTA transfers according to this ESP32 OTA troubleshooting guide.
✓ Keep Firmware Small
Large binaries slow updates and risk exceeding partition limits. Remove unused libraries and debug prints when possible.
✓ Always Test the Fallback
Simulate failed updates to confirm the device boots correctly from the other partition.
✓ Use Versioning
Include a firmware version number in your code. This helps you track what the device is running and whether an update succeeded.

Common OTA Problems and How to Fix Them

ESP32 OTA troubleshooting: Common issues and how to resolve them during over-the-air updates.
IDE Not Detecting the Device
• Your PC and ESP32 may be on different VLANs.
• mDNS might be blocked by the router.
• Firewall settings can hide the network port.
Upload Fails Mid-Transfer
• Weak Wi-Fi signal.
• Browser timeout during ElegantOTA upload.
• Device running out of memory.
Wrong Partition Scheme
If the ESP32 doesn't have app0/app1, OTA will not even begin. Double-check the board settings.
Firmware Too Large
The new binary must fit in the inactive partition. If it doesn’t, reduce memory usage or pick a partition scheme with larger OTA slots.

Conclusion

This ESP32 OTA update tutorial shows how OTA transforms the ESP32 from a simple development board into a scalable, remotely manageable device.OTA updating transforms the ESP32 from a simple development board into a maintainable, scalable, and remotely manageable device. Whether you choose ArduinoOTA for quick local development or ElegantOTA for a more polished, user-friendly web interface, both methods eliminate the need for physical access, as noted in this Arduino OTA documentation.With proper partitioning, basic security measures, and a few best practices in place, OTA becomes a reliable part of your project’s lifecycle—allowing your ESP32 devices to evolve long after they’ve been deployed.