What are Sensor Indexes and Sensor Read Keys?

what is Sensor Indexes and Sensor Read Keys and how do i get these parameter?

A sensor index is a number corresponding to a specific registered sensor. A sensor index can then be used to query data for that sensor from our API. You can examine our Sensor Index article for further information and instructions on how to obtain an index.

Sensor read keys are similar to sensor indexes. They are alphanumeric and are required to obtain the sensor’s data from the API if it’s privately registered. Information on obtaining a sensor’s read key is found in my response to this How do i get my sensor Read Key post.

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Hi Joshua,

Thank you for providing me with the detailed information on sensor indexes and read keys. It’s really helpful!



Hi Joshua,

I have another question. I’ve tried to use the PurpleAir download tool to download data from my sensor, but when I select and insert the details and press “Download”, the software crashes and gives the error “Failed to get data from API”. Any idea what might be causing this?


Hi Justus,

At the moment I’m unsure of the exact cause of the error. If you can replicate the error a screenshot of the error message would prove helpful. Any of the additional information would help us determine the cause of the error as well:

  • Have you encountered this issue multiple times?
  • When you say that the software crashes, does the Data Download Tool close, or is an error message displayed in the “Progress” tab?
  • Is “Failed to get data from API” the exact message shown?
  • Please provide all information entered on the “Download” tab of the Download Tool, and we’ll see if we can replicate the issue. This information includes:
    • Sensor Index
    • Sensor Read Keys
    • Start Timestamp
    • End Timestamp
    • Average
    • Fields

You’re more than welcome to reply to this community post or send us an email. Whichever is most convenient for you.

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Hi Joshua,

Thanks for reaching out. I appreciate your assistance in troubleshooting the error with the ‘Download’ tab of the Download Tool. Here’s all the necessary information you requested:

  • Yes, I have encountered this issue multiple times.
  • When the software crashes, the Data Download Tool closes and there is an error message displayed in the “Progress” tab but since the software closes before i can read the error. I have attached a video for this.

Now, regarding the information entered on the ‘Download’ tab of the Download Tool, here are the details:

  • Sensor Index: [Enter Sensor Index] 95859#13.16/-6.81892/39.25889
  • Sensor Read Keys: [Enter Sensor Read Keys]
  • Start Timestamp: [Enter Start Timestamp]
  • End Timestamp: [Enter End Timestamp]
  • Average: [Enter Average]
  • Fields: [Enter Fields]

NB: I have attached screenshots and a video.

I hope this provides enough information for you to replicate the issue. If you need any further details or clarification, please let me know. Feel free to reach out via email or reply to this post.

Thanks again for your help!

Best regards,

(Attachment 20240125_095507.mp4 is missing)


Thank you for the detailed information! I’ve been able to replicate the issue, and the crash appears to be caused by the special characters entered after the sensor index. We’ll address this bug to avoid any future crashes.

A sensor index is a number without any punctuation, alphabetic, or special characters. The index within your screenshot would be 95859. The extra information included after indicates the zoom level, latitude, and longitude of the map’s view when you copied part of the URL.

Hey Joshua,

Thanks for getting back to me and providing the detailed information. I really appreciate it! I understand now that the crash was caused by including special characters after the sensor index. Moving forward, I will make sure to only include the sensor index itself.

Thanks again for your assistance!