We are a team of rouge developers from all over the world. We started with the basic idea that we needed to get a tool in the hands of everyone to allow them to know if they had possibly been infected or not. The current virus that's wreaking havoc on the world is a silent killer- people don't know they're infect for days! So we came up of a way to curb the community spread between individuals.

Initially, the project started small between two of us, but slowly it grew and we have a team of fantastic engineers, security, product, and medical experts from around the globe!

Our idea started with the code name: "Save The World". That's our inspiration, that's our goal, and regardless of the outcome of this hackathon, we will continue to do so.

Most people agree that tracking is an invasion of privacy and something we'd rather not have. However, cities are being locked down, and citizens are prevented from moving freely. It's only a matter of time before people start to get too cooped up and we need to let people get back to their daily lives- and once the curve is lowered, the restrictions will ease. However, this is when things will become dangerous; it will become the second spike of the Covid-19 virus.

Guardian will be especially useful as we enter the "long tail" of this pandemic. People will want to get out of their houses and start moving around again. Guardian will help eliminate this pandemic because without a system like this we may see second and third spikes in virus spread. Guardian is targeted for the current pandemic, but would be useful in the case of future outbreaks/pandemics.

We are developing a lightweight tracking and alert/contact system that can integrate with verified test results. This system must do everything possible to preserve a high level of privacy and be simple enough that everyone and anyone can use it.

We are currently working with both healthcare and privacy/security experts to validate the concept and product.


A Privacy Focused, Scalable, Community Driven, Verifiable Infection Risk Alert System

Guardian is strongly authenticated mobile phone application, which works in conjunction with a secure data collection backend server.

This system is based on the premise that the rapid spread of COVID-19 is primarily due to people moving about when are unaware that they are infected. [Community Spread]

Countries that have controlled spread have employed mainly two methods (including hygiene guidelines) in combination:

  • historic tracking
  • testing

Users install Guardian on their mobile phone, and then they mostly forget about it!

They can do two things with Guardian:

  • They will get alerts when they have been close to someone who has reported symptoms, or has been verified to have tested positive,
  • They can report symptoms, or confirm a positive or negative test result.

What do alerts look like?  Initially they will be very simple: "Alert, yesterday you were 20 feet from someone for 10 minutes who reported symptoms matching COVID-19".

This system can save lives with the potential for mass installations because:

  • It is simple, it has to the most simple app possible that anyone can use,
  • It is secure,
  • It is scalable,
  • It enforces user privacy and anonymity
  • It can be integrated to healthcare systems doing wide-scale testing.

Some key points:

  • Alerts are calls-to-action. They ask the user to do a self-inspection, e.g. do they have a fever. They remind the user to follow instructions - social distance, hand-washing, etc. They ask you to report if you are sick.
  • Maps are not that important - we have to stop staring at maps. What is important your historic location track - who were you close to, and who was close to you.
  • Real time is not important - If someone starts to feel ill, they usually will make there way to their home before they report this. So the location of report is not that critical, but time of first noticed symptoms is.

Some key assumptions:

  • People want to do the right thing, when they are sick they will stay home,
  • If given the opportunity they would be willing to anonymously warn others who they might have put at risk.


The goal of this system is to give users some peace of mind that there is something they can do with very little effort that can have a large impact on the outcome of the pandemic.

This system uses GPS location tracking, however, the motivation is simply to alert users when they have been close to someone who has been verified to have COVID-19. It also has a mechanism to report themselves as being diagnosed with COVID-19 (and verified by healthcare workers).

This system is based on the premise that the rapid spread of COVID-19 is primarily due to people moving about with they have mild systems and are unaware and untested. It further assumes that when diagnosed, a person will self-quarantine. This diagnosed person will feel remorse for potentially putting others at risk, and hence will be willing to share more detailed information about their movements during the pre-diagnosis time-frame. This is a guilt driven application.

However, even though your locations are shared, no other users will know your name or know exactly where you have been - it's really none of their business. A persons movement is their own private information. What Guardian will show is a risk factor based upon you own movement.  (see diagrams)

These alerts will serve to remind persons that there are still new cases of COVID-19 being diagnosed. Their reaction should be to continue preventive measures such as social distancing and proper hand washing hygiene - an alert that you were close to someone recently diagnosed will make you think twice about going to work when you feel sick.


Social distancing and other preventive measures are hard to communicate to people. Over time people get lax with their personal preventive measures. At the same time draconian big-brother measures of citizen location tracking doesn't feel good. We can make a system that has a high level of privacy, is scalable, and primarily community driven. Over time it can get better, and use verifiable healthcare submitted information can be incorporated.

This application mostly does nothing! You install it, and forget you are using it. Occasionally you get an alert. If you unfortunately contract COVID-19 then you can report it and alert others. But it is as accurate as possible. It will compare your locations to others down to 5 minutes and within the accuracy of GPS.

People need to stop searching for infected persons or areas on maps where they shouldn't go, and instead consider themselves as potential carriers of the infection. No matter where a person goes, or how few people are at a location, there is still a chance that someone else at the same location could be a carrier (or you could). Guardian's core principle is to use historic tracking combined with testing as the basis for alerts - proximity and transmission can happen at any location.

Gates called for a "national tracking system similar to South Korea, saying that "in Seattle, the [University of Washington] is providing thousands of tests per day but no one is connected to a national tracking system" and that "Whenever there is a positive test it should be seen to understand where the disease is and whether we need to strengthen the social distancing."


This system needs to work anywhere in the world. The easiest way to do this is to just use mobile phone numbers. The goal is for users install Guardian application on their mobile phone, and then they mostly forget about it until they either are alerted they were in proximity of some who may be infected, or has confirmed to be infected.

The system uses an innovative multi-resolution location private intersection method to preserve privacy but still allow accurate historic determination of proximity.

The user's historic location data is only stored on the user's own mobile device, expect for large scale location movements which are tracked by the server. The security principle here is "the server can't leak data It has never had or never seen!". However, when one user is reporting themselves as infected (self-diagnosis or actual test confirmation by health officials), then a precise path intersection can be done by using private intersection methods. Private intersection is the preferred method used in many healthcare applications to preserve privacy.

Not only does this architecture preserve privacy, it also gives scalability by using distributed computing, and preserves device battery life.

Tracker Application

This is one of our major feature sets, but unlike most other applications, we are focusing on the data, battery, and accuracy of the application rather than heavy front facing features.

The Guardian smartphone application tracks the users position throughout the day - every 5 minutes it checks your position and locally stores your position track to your phone. The application then reports to the cloud service when a user enters a new region during the day, as well as at the beginning and end of day

Note: your precise position data is stored securely on your phone.

How we Built It

We have built two separate parts to create Guardian. The first being our backend protocols which are built in Elixir. The second is our client which we are building in a combination of React Native and Redux. The two are separate and only communicate through a documented protocol in order to preserve maximum privacy of the user.


  • People want to do the right thing, when they are sick they will stay home,
  • If given the opportunity they would be willing to anonymously warn others who they might have put at risk.

Challenges We Ran Into

Healthcare testing in the US is so up in the air right now- there is no standardization practice in place for a test kit to be verified. We've had to come up with a brute-force way to get around this issue.

Guardian can also be used as a first-contact tool for healthcare professionals.


People will spoof it

  • You must be registered. This limits some amount of spoofing.
  • Your entire time-location track is uploaded when you report you are infected.
  • Your time-location track is encrypted and must be believable.
  • Moderation could limit spoofs
  • We could use healthcare verification of testing (some sort of test-id, etc., that can be verified or entered by healthcare worker).

It creates panic.  The alert you receive is for your movements on previous days, there is nothing you can immediately do to change the situation. Also, the location itself is not the problem - this is not a chemical spill.

GPS is not very accurate.  What use is it in an apartment for example? True. But then again, it's just letting you know that this is indeed real and people are still being diagnosed. It seems that a lot of systems are focusing on targeting the subject (infected person) too closely and trying to single an individual which is very privacy invasive, and works against the goal of communicating the pandemic to the larger public and getting participation in such a system. As such, accuracy is actually working against broad usage of such applications.

I want to know where the infected people are. We do not plan to track infected persons - because they probably wouldn't give consent anyways because they are supposed to self-isolate.

This can harm business and put people in danger  We do not plan on showing maps to users that include exact locations and combined with other paths - because the risk is that people will start to think some location is bad, such as a business. It's not the location, it's just random - you were in the wrong place at the wrong time!

Accomplishments We're Proud Of

Well, this is some of our secret sauce. Guess we have to save that for a surprise discussion. :)

What We Learned

The world is filled with people who want to help. It brings us hope!

What's Next for Guardian

Regardless of the outcome of this hackathon, Guardian will continue to move forward. We firmly believe that this is something the world needs. And our supporters also believe so too. Our team will continue to volunteer their time and effort to tackle this global crisis- and the crises that follow.

Thank you!

Try It out



elix, react-native, redux

Devpost Software Identifier