Evidence Recorder


Evidence Recorder is a phone app for recording voice conversations for use as neutral legal evidence. The app is entirely operated by voice call and can be used with any cell phone. The app was created in response to a challenge by the Southern Poverty Law Center.

According to the  Southern Poverty Law Center, migrants report being subject to unconstitutional law enforcement activity, such as being stopped, asked for papers and harassed. Since there is no evidence of the encounter, it frequently becomes a "he said, she said" situation where law  enforcement officers deny having harassed the migrant. Evidence Report aims to empower migrants by allowing them to record evidence using their cell phones. 
The application is operated entirely by voice call.

  1. Call (650) 265-1688 and place your phone on speaker mode.
  2. You will hear voice instructions and a beep. Recording will start after the beep.
  3. You may record up to one hour of audio.
  4. When the recording is complete, hang up.
  5. You will receive a SMS message with instructions for how to play back your recording.
Stealth Recording
  1. Call (650) 567-5990 and place your phone on speaker mode.
  2. Recording will immediately and silently start.
  3. You may record up to one hour of audio.
  4. When the recording is complete, hang up.
  5. You will not receive the SMS message with instructions. To play back the recording, follow the playback instructions on this page.
Note: Stealth recording may not be legal in all jurisdictions.


  1. Call (650) 567-4386.
  2. Press the number of the recording, then press the # key.
  3. Recordings are ordered from the least recent to the most recent. For instance, if you have 5 recordings, the least recent recording will be number 1, and the most recent recording will be number 5.
Our application design has several advantages. Although existing voice recording applications exist, they usually require an Android or iPhone. On feature phones, voice recording applications are often missing or limited to recording a few minutes of audio, which is insufficient for recording an entire encounter. Evidence Recorder can be used on any cell phone, not just smartphones, and thus lowers the barriers of access.

The application stores the audio recording, the originating phone number and the timestamp. Because the recordings are stored remotely, they cannot be destroyed by tampering with or confiscating the phone. This is in contrast to other recording apps, which store data on the phone itself.

It is hoped that the act of recording a conversation overtly will encourage law enforcement officers to treat users with courtesy. However, if the user fears being intimidated by the law enforcement officer, the user may use the stealth mode to covertly record the conversation without alerting the other party. Note that stealth mode may not be legal in all juristrictions.

The application  can support other native languages of migrants. Currently, the application supports English and Spanish. To access the application with Spanish voice instructions, call (650) 567-4453 for record and (650) 567-4363 for playback.

An online website at http://www.evidence-recorder.com/ contains complete instructions for usage in both English and Spanish.

The online website also provides a page for users to download audio recordings of conversations. This feature is particularly useful for migrants who switch between prepaid "burner" phones and frequently change numbers. This allows them to retrieve recordings from older numbers that they may no longer have access to.

We hope that this app will be useful for empowering its users to reduce unconstitutional law enforcement behaviors.

We would like to thank Jim Knoepp of the Southern Poverty Law Center for motivating the project and providing valuable feedback.


YouTube Video


Yifan Mai (myffical@gmail.com)
Roman Zhovtulia (roman@WebServiceCenter.net)




Best Mobile App
Best Overall Project