General question on Blynk system Architecture and license for non-commercial use

Hi - I am a Blynk newbie, although I am pretty familar with various Cloud IoT technologlies (which is part of my professional business).

In my leisure times I am a Garden Modelrailway Club member and I am controlling all kind of actors (sensors) such as locomotives, switches, signals etc via my Smartphone in WiFi environments.

Actors / Sensors are connected via RasPIs and Espressif Microcontrollers (all acting as IP- Servers/nodes in a model railway network).

On user side I use a Smartphone based interface (the NETIO App Framework NetIO APP ) for years now - until today.

NETIO is capable to set up IP based connections to all kinds of Network nodes / devices and let the user control their devices with knobs, sliders, etc. - always without the need of a Cloud server inbetween.
All my devices are all self-programmed in C++ / python / shell scripts (with socket interface connections)

As NETIO is being discontinued end of '21 I am looking for a substitute - Blynk looks very interesting.

Now my questions please:

  1. List item

Does the Blynk System Architectures demand for a (Blynk) Cloud server as an intermediate node to connect to my devices. Would mean Blynk is not usable for me - as Internet connectity (mobile networks) are not always available ?

  1. List item

Are there symbol / functionality / library limitations in quantity and/or quality (affecting the number of switches / locomotives / signals or limitations to functionality) when using a non-commercial license ?
20 devices limit per Smartphone is not a problem - would match, as switches and signals are controlled by a central node, 19 locomotives would be sufficent per Smartphone.

But what about “max 2000” ? What does this mean - symbols (sliders, knobs in the GUI)?

  1. List item

Is the non-business use “friendly tolerated” by your business?
I do note want to “misuse” a non-commercial license when hobby activities are not welcome in a professional business environment.
Being a Senior Manager in world-wide professional Cloud IoT business (as system supplier to mobility operators) I can fully understand that your strategy is fully concentrated on professional deployment and therefore hobbyist are considered ballast.

Nevertheless, it could be seen as an added value that also hobbyist can contribute good ideas and can also give valuable hints when tracking down errors.

Thanks in advance for your time and effort!

Best Regards

You can easily set-up a local Blynk server, which would overcome the internet connectivity issue.
It would also allow you to grant yourself unlimited energy at no cost, and remove any device number restrictions.

The ‘problem’ with Blynk is that each device needs to have its own unique Auth token, and that if you want one device to talk to another then you need to use Bridge code to send data to the Auth token of the other device.
The app can see and control an unlimited (as far as I know) number of devices so provided the control is manual and done 100% via the app then Bridge code isn’t needed.

Putting tat into a context that may be more relevant to your application…
Say you have a proximity sensor connected to a standalone device, which needs to control a signal which is also connected to a standalone device, then Bridge code would need for the proximity sensor device to send a command to the signal device.

Personally, I prefer a a different approach, which is to use MQTT to control and collect data from each device. I then use Node-Red, which is a visual programming system, to provide the interface to Blynk via a plug-in.
There is a possibility that a NETIO plug-in for Node-Red could simplify your transition, by allowing your current devices to communicate with Node-Red without any changes to your device software.


Thanks very much for your answer.

Compatibility to NETIO is not my problem (any more) - I am going to start from scratch now for the NETIO part …!

I have understood by your explanation (thanks) that the needed server could be installed “on premise” instead using an Internet connection - fine!

My problem (at the moment) is - I need to find a user friedly Smartphone Interface first, by which I can easily set up project GUIs (without “native” Android programming, e.g. KOTLIN based).

I am looking for a “framework” with editor for symbols (widgets ?) like sliders, knobs, ASCII fields etc. which I can easily drag, drop change in geometry etc. in edit mode - selected from a libraries, vary in size in color and parameterize with/by values.

Pls. have a look here NetIO APP (some projects are mine). Blynk exactly would offer me similar possibilities (symbol / widget library and editor) at a first glimpse.

At server side (on a Raspi or ESP32 - for example installed in a locomotive) I am running my C++ sever application which is controlling GPIOs in different methods (ON OFF, PWM for H-Bridge, etc.). This application code I want to keep / adopt it to a new protocol between Smartphone and the Server where the application is running on.

The protocol could be MQTT, or any other Real Time protocol, even REST HTTP could be an option with an additional web server installed on the Raspi as a server based communication front-end.

openHAB could be another alternative to migrate to - at this moment - starting from scratch anyway. I am evaluating PROs and CONs of everything being offered in the Internet.

Key question remains - am I limited in the Blynk symbol library by the “non-commercial” license? Am I limited in functionality?

Sorry for my drilldown - thanks for your support anyway!

Best Regards

The Blynk product that’s supported here, and available as an app download for Android/iOS has a strict “non commercial” policy, but your usage doesn’t infringe that at all.
The system is what you see, so if it suits your needs then go with it.
If you need more app functionality then choose something different.


Hi Pete, thanks for your valuable advice.

I have watched youtube - seen a Blynk project example of your company. That was very helpful - I have realized that only 10 widgets will eat up the 2.000 free energy points per project.

As I intend to have more widgets on a project Blynk will be not affordable in my non commercial project.

I need to look for other alternatives.

Thanks & Best Regards

Blynk is nothing to do with me, I’m simply a user!

I’m guessing that you missed this bit…

The energy units are there as a way of Blynk covering some of the hosting costs for the cloud servers.
When you host your own server you can give your self a million or more free energy points if you wish…


Hi Pete,

Thanks very much for correcting me - this of course is very good news, worth to give Blynk a try. You made my day …!

In general - the configurable GUI is the most valuabale part for me (at the beginning) - with regard to connectivity / protocols I can help myself using a bridge or gateway or somethng else in between. Nevertheless, using modern technics like NodeRed, MQTT etc. would be the final goal to implement, socket programming is a bit old fashioned and stiff.

I will start immediately in the next days and download the server, playing around a little bit for first experiences!

Thanks & Best Regards