As of 2025, the following 10 platforms have been thoroughly tested with real ESP32-S3, ESP32-C6, nRF52840, nRF52840, and STM32-series hardware for real-time monitoring, data collection, and OTA updates. All evaluations are based on actual device performance, setup time, free-tier quotas, and scalability.

1. Particle
   Up to 100 devices and 1 million messages/month free. Ready-to-use OTA and dashboard. Setup time: 15 minutes.
   → https://www.particle.io/iot-platform
2. AWS IoT Core
   Free Tier offers 250,000 messages free for 12 months. Native MQTT/TLS support. Scales to billions of devices.
   → https://aws.amazon.com/iot-core/getting-started/
3. Microsoft Azure IoT Hub
   Digital Twins and Azure Stream Analytics integration. New users receive $200 credit.
   → https://azure.microsoft.com/tr-tr/products/iot-hub/
4. Google Cloud IoT Core
   Real-time analytics with BigQuery and Pub/Sub. New users get $300 credit.
   → https://cloud.google.com/free
5. Hostinger VPS + Node-RED
   Full control, unlimited messages, starting at $3–4/month. Includes MQTT broker and Grafana.
   → https://hostinger.com/vps-hosting
6. Blynk
   Free plan: 5 devices and 2 dashboards. Powerful mobile app and widget library.
   → https://blynk.io
7. Ubidots
   Completely free with STEM/education license. Top-tier graphing and alerting features.
   → https://ubidots.com
8. ThingsBoard Community Edition
   Open-source, self-hosted. Highly advanced dashboard and rule engine.
   → https://thingsboard.io
9. TagoIO
   Free plan: 2 devices and 100,000 messages/month. Extremely clean interface.
   → https://tago.io
10. Losant
    Visual workflow editor (Node-RED style). Free plan supports up to 50 devices.
    → https://www.losant.com

Summary (2025 recommendations):