Node-RED is useful.How many sensors can the Node-RED platform support for access?
Unlimited! Resource dependent! All based entirely on guess work!
To be honest, your question is far too vague. For example, what type of sensors? How are they connected to node-red ? What is your hope or expectation? 20?, 2000? 2 million?, What do you intend on doing with the data.
Also what hardware/OS do you want to run node-red on?
Offload most of the communications direct from the sensor to an MQTT broker keeping the data frequency and size to a modest level and even modest hardware should support hundreds if not thousands or more.
Use MQTT (your sensors not directly connected to the Node-red server) and a reasonable frequency of sensor readings.
I tried with Node-red on a Raspberry Pi Zero 2, a very low power server.
It was easily able to accept and perform simple processing on 10 MQTT messages per second.
May be deploy on servers with different parameters. What tools are available to verify performance.
Attempted to connect over 100 sensor devices using Node-Red
I get the feeling you are not familiar with Node-RED.
You should spend a little time understanding what it is, how it works etc.
That will help you formulate questions that can be answered.
For example. What type of sensors. What will you do with the data? How frequently will they be updating? Are you attempting to get "realtime" data?
If these are accessed via MQTT - simple, even a Rasperry Pi Zero could do that.
If these are accessed via HTTP - still fairly lightweight
However, if these are 100 hard wired devices or 100 separate Modbus Masters each with 1 sensor - that is much more difficult.
You NEED to provide some context.
I have used Node RED multiple times in engineering. It all works well. But I want to know how to test the limit of the number of connected sensors. Because different owners use different servers and sensors. If a large number of sensors (more than 1000 devices) are connected using the HTTP protocol,do I need to consider stress testing of the interface?