# What Is an Open IoT Platform?
## 3 Results
### Q1: What IoT Platforms Have Been Characterized as Open?  
To address this question we analyzed the data extracted from F7 and F8 stated in Table 1, i.e., open IoT platforms in \"use\" and \"indicated\". Table 2 reveals that there are 25 IoT platforms characterized as open by the studies. We note that there are seven open IoT platforms that are mainly used within the research community, whereas the other platforms are used only once or twice. For example, Figure 3 shows that most used open IoT platforms are NodeMCU and ThingSpeak, which together held a share of more than 70%, and are followed by FIWARE, Mobius, Kaa, OpenIoT, and ThingsBoard.  
Figure 3: IoT platforms characterized as open based on studies that were classified as “use”, totaling to 134 papers.  
Figure 2: Distribution of the yearly publications related to open IoT platforms and articles with no explanation about open IoT platforms.  
Moreover, there is an interesting correlation between the referred open IoT platforms when they are \"use\" versus \"indicated\" by the researchers and practitioners, which is presented in Figure 4. In particular, we noticed that the researchers who make use of NodeMCU often do not refer to it as an open IoT platform; however, this is the case as soon as they are providing a description of it. We note that on Wikipedia, NodeMCU is referred to as an _open-source IoT platform_; however, its official homepage refers to it as _an open-source firmware and development kit_, which we think is an interesting observation and we agree with the latter. This also outlines that researchers tend to get more easy information from the web.  
Furthermore, OpenIoT is mainly used by partners and researchers that were part of the project ICT OpenIoT Project FP7-ICT-2011-7-287305 and that its GitHub repository has received no updates since November 2015, which by coincidence correlates well with the end date of project (28 February 2015) as stated by the grant agreement. The requirement of the IoT platform being ready to use and having an active community has gained momentum and become a key criterion in order to be identified as an IoT platform. By coincidence, platforms that either have not had their code updated since December 2015, or with no activity on their website during the same period of time, are considered no longer under active development and therefore do not satisfy the requirement to be identified as _available_ IoT platform [32].  
\begin{table}
\begin{tabular}{l l l l l l l} \hline \hline \# & **Used/Indicated Platforms** & **Open-Source Open** & **Open** & **Open** & **Not** \\  & & & **Standards** & **APIs** & **Data** & **Specified** \\ \hline
1 & NodeMCU & 45 & 1 & & & 1 \\
2 & ThingSpeak & 29 & 1 & 4 & 2 & 12 \\
3 & OpenIoT & 13 & 1 & 4 & 2 & 1 \\
4 & FIWARE & 13 & 2 & 3 & 1 & \\
5 & KAA & 9 & & 5 & & \\
6 & Mobius & 6 & & 3 & & \\
7 & ThingsBoard & 6 & & 1 & 1 & \\
8 & IoTivity & 3 & 1 & & & \\
9 & Oliot & 2 & 1 & & & \\
10 & OM2M & 2 & & & & \\
11 & Arduino Raspberry Pi & 1 & & & & 1 \\
12 & Arduino Uno ESP8266 & 1 & & & & \\
13 & Mobius & & & 1 & & \\
14 & Contiki OS & 1 & & & & \\
15 & Cosm OS & 1 & & 1 & & \\
16 & Emon & 1 & & & & \\
17 & MediaSense & 1 & & & & \\
18 & RIOT & 1 & & & & \\
19 & Tacit & & & & & 1 \\
20 & Heroku & 1 & & & & \\
21 & FLIP & 1 & & & & \\
22 & IoTMakers & & & 1 & & \\
23 & Tridium & & & & & 1 \\
24 & VITAL-OS & 1 & & & & \\
25 & Californium & 1 & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 2: The open IoT platforms identified in categories “used” and “indicated” in connection to the identified openness types.