General Configuration

Server configuration settings
System Status
If 'offline', normal users will be denied access to all pages.
Custom message to display to users when system is offline:
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HTML may be used in order to adjust the style of the text or to display links, images, etc.
Language Displayed for Global Pages
If you wish to translate the English text in REDCap into a new language and create a new language file, you may go to the Language File Creator/Updater page and follow the instructions. To download any already translated language files in order to utilize them in REDCap, visit the REDCap Community Language Library.

Language files are located on the server at /var/www/html/redcap/languages/
Enable a Read Replica database server to improve system performance?
To help offset server load if the REDCap system has been experiencing routine slowness, REDCap can connect to a read-only, secondary database server that uses MySQL/MariaDB replication to stay in sync with REDCap's primary database server. The Read Replica server will be utilized only for read-only operations in the following places in REDCap: viewing reports, exporting data (including API exports), viewing record status dashboards, viewing and exporting the project logging page (including API logging exports), using the data search tool, viewing the scheduling page, executing data quality rules, viewing project dashboards, and viewing the Control Center's System Statistics and User Activity Log pages.
Read Replica functionality is not available for use because the connection variables were not found in database.php.
NOTE: The Read Replica is only recommended for use if you have been experiencing performance issues with your REDCap server, such as a routine or off-and-on slowness. Before enabling the Read Replica feature, it is advised that you explore other ways to improve database performance first, such as adding more RAM and CPUs to your database server to see if that provides some improvement. If those things do not help, then using the Read Replica might be a good option.
How to set up the Read Replica feature
The effort of enabling the Read Replica functionality is very minimal once a replica server has been created and is successfully replicating from the REDCap primary database server. Most of the work will be simply setting up the replica server. See the instructions below regarding how to enable the Read Replica feature.
  1. Set up new database server and enable replication to primary: First, you need to set up a new database server that closely matches the specs of your existing REDCap database server. Ideally, it should be the same version (or very close version-wise) of MySQL/MariaDB as the primary server, and it is recommended that the replica have the same RAM/CPUs or slightly less than your primary server. Simply follow the standard procedures for setting up MySQL/MariaDB replication on that server so that it is successfully replicating in real time from the REDCap primary database server. Once replication is enabled, it might take many hours for the replica to finally catch up to the primary server. NOTICE: The REDCap development team is purposely not providing specifics on how to set up MySQL/MariaDB replication because they are not experts in this area and because this should only implemented by an IT specialist, such as a DBA, who has expertise in this area. If you or your IT folks do not know how to implement database replication, then enabling the Read Replica feature should *not* even be considered.
  2. Add connection variables for the replica to database.php: Create a MySQL/MariaDB 'user' on the replica server so that REDCap may use that user to connect to the replica. Then open the /redcap/database.php file for editing on your REDCap web server, and add the replica connection variables to the file, as seen below. 
    $read_replica_hostname   = 'your_replica_host_name';
$read_replica_db     	 = 'your_replica_db_name';
$read_replica_username   = 'your_replica_db_username';
$read_replica_password   = 'your_replica_db_password';
    If the replica requires an SSL/TLS connection (i.e., MySQL over SSL), you will also need to provide the additional connection variables below.
    $read_replica_db_ssl_key  	= '';	// e.g., '/etc/mysql/ssl/client-key.pem'
$read_replica_db_ssl_cert 	= '';	// e.g., '/etc/mysql/ssl/client-cert.pem'
$read_replica_db_ssl_ca   	= '';	// e.g., '/etc/mysql/ssl/ca-cert.pem'
$read_replica_db_ssl_capath 	= NULL;
$read_replica_db_ssl_cipher 	= NULL;
$read_replica_db_ssl_verify_server_cert = false; // Set to TRUE to force the database connection to verify the SSL certificate
  3. Enable the Read Replica system setting on this page: Once 1 and 2 above have been completed, reload this page (General Configuration), after which the Read Replica 'enable' drop-down should no longer appear as read-only/disabled. Enable the Read Replica by selecting 'enable' and saving the page. Then visit the main Control Center page or Configuration Check page, and if they display a warning that the Read Replica might be offline or can't be connected to, then double check that the correct replica connection variables were added correctly to database.php.
  4. Monitor the Read Replica: If REDCap can connect to the Read Replica successfully, the replica will be utilized (rather than the primary database) on specific pages throughout REDCap where read-only processes are performed. The replica can be seen and its activity observed on the Database Activity Monitor page. If the replica's lag time rises higher than 3 seconds, then it will not be used until its lag time from primary is 3 seconds or less. This is to prevent users from viewing 'stale' data from the replica in case the replica lags too far behind the primary server.
Automatically send basic statistics to REDCap Consortium?    (What stats are sent?)
If sending stats manually, you will need to click the button at the bottom of the Control Center's Notifications & Reporting page.
REDCap base URL
The base web address of your REDCap installation (e.g., https://redcap.vumc.org/, https://YOURSITE.edu/redcap/). This will be used to construct the URL when users navigate throughout REDCap as well as for contructing survey URLs included in email invitations.
Survey base URL (optional)
Alternative REDCap survey base URL (leave blank if same as REDCap base URL above)

This base URL will only be used when constructing survey URLs (e.g., when sending invitations to survey participants). For all other URLs in REDCap, the REDCap base URL will be used. This feature can be useful if you wish to use a different web address for surveys than for the web address where users log in (e.g., when using a reverse-proxy server or separate web server for surveys).
If using a proxy server, please specify the proxy server hostname and port.
(Proxy setting is ONLY used for outgoing requests from the server.)

If using a non-standard port, then append a colon and port number to the end of the hostname. Also, make sure to prepend http:// or https:// to the hostname.
(e.g., https://10.151.18.250:211)
If using a proxy server that requires username-password authentication, provide the username and password separated by a colon.
(Proxy setting is ONLY used for outgoing requests from the server.)

e.g., redcapuser:MyPassword1234
Is this REDCap server a development/test/staging server?
If 'Yes' is selected, then PHP error reporting will be enabled to display all errors to help with debugging purposes on non-production servers.
Can REDCap server access the web (make outbound HTTP calls)?
If this REDCap server has no internet connectivity or cannot access the outside World Wide Web, then set to 'No'. If it cannot access the web but is left as 'Yes', it could cause some pages/services to be extremely slow or not load.
REDCap Hooks
To utilize REDCap hooks, you must specify the full file path to your Hook Functions file, which is a PHP file on your REDCap web server that contains all your hook functions. You may place the Hook Functions file in any directory you wish, and you may name it anything you wish. Once you have created it, provide its full file path here so that REDCap may then begin to utilize any hook functions inside it. For more info on REDCap hooks, see the documentation by clicking the 'Plugin, Hook, & External Module Documentation' link on the left-hand menu
Full path to your PHP file containing your REDCap hook functions
Example: /var/www/html/redcap/hooks.php

  Configuration for Outgoing Emails
Set a Universal FROM Email address for ALL emails sent from REDCap (optional)
TIP: You probably do not want to use this option unless REDCap is unable to send out some or all outgoing emails successfully (often due to email providers blocking emails whose 'From' address does not match the domain name of the REDCap server (e.g., sending an email from joeuser@gmail.com from the server https://redcap.vumc.org).

Example: no-reply@vanderbilt.edu, donotreply@chi-redcap.dshs.texas.gov
Leave this blank (default) to have all emails sent from REDCap have the 'From' address be that of the sender. If an email address is provided above, then *all* emails will have it as the 'From' address (although all emails will still have the 'Reply-To' value as the sender). This option is useful if your SMTP email server refuses to send emails from an external domain address (e.g., Gmail, Yahoo).
Suppress usage of the Universal FROM Email address for specified email domains
By default, the Universal FROM Email address will be used for all outgoing emails, but if one or more domain names (e.g., vanderbilt.edu) are specified here, then the Universal FROM Email address will NOT be used for any outgoing emails in which the FROM/sender's email address matches one of those domains, but instead the FROM/sender's email address will remain as-is.

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Separate each domain on a different line. See example below.
vumc.org
vanderbilt.edu
Utilize the Display Name in all outgoing emails?
Display names are used in emails to include a person's name (for example) next to the sender's email address in the recipient's email client in order to provide further context regarding the sender's identity. For example, 'Joe User '. If the display name is excluded/disabled here, then the recipient will merely see the sender's email address in their email client and not the sender's name, and additionally, all options for adding a Display Name in the user interface will be hidden (e.g., for outgoing survey invitations).
REASON FOR USAGE: The display name feature might need to be disabled if your institution is having a disproportionate amount of emails not being received due to email servers blocking them, sometimes due to the usage of the display name. If you are experiencing this kind of issue, we recommend testing both with and without the display name setting turned on in order to test if the display name might be the cause of emails not being received.

  Mandrill Email Configuration(optional third-party email configuration)
When sending outgoing emails, REDCap can utilize the Mandrill API for sending emails as an alternative to using the REDCap web server's default methods that send emails via PHPMailer. You first need to set up an account on the Mandrill website https://mandrillapp.com/api/docs/, which will give you access to an API key that is connected to your MailChimp account. NOTE: You will need to create an account and generate the API token there in order to use it here in REDCap. Follow all instructions on the Mandrill website for obtaining and using the API token.
Mandrill API Key


  SendGrid Email Configuration(optional third-party email configuration)
When sending outgoing emails, REDCap can utilize the SendGrid API for sending emails as an alternative to using the REDCap web server's default methods that send emails via PHPMailer. You first need to set up an account on the SendGrid website https://app.sendgrid.com/guide, which will give you access to an Email API key that is connected to your SendGrid account. NOTE: You will need to create an account and generate the API token there in order to use it here in REDCap. Follow all instructions on the SendGrid website for obtaining and using the API token.
SendGrid API Key


  Mailgun Email Configuration(optional third-party email configuration)
When sending outgoing emails, REDCap can utilize the Mailgun API for sending emails as an alternative to using the REDCap web server's default methods that send emails via PHPMailer. You first need to set up an account on the Mailgun website https://app.mailgun.com/app/domains, which will give you access to an Email API key and Domain Name that is connected to your Mailgun account. NOTE: You will need to create an account and generate the API token there in order to use it here in REDCap. Follow all instructions on the Mailgun website for obtaining and using the API token.
Mailgun API Key
Mailgun Domain Name
Mailgun base URL (optional)
If left blank, the base URL https://api.mailgun.net will be used. Other options include the following base URL for the EU region: https://api.eu.mailgun.net.

  Azure Communication Services - Email Configuration(optional third-party email configuration)
When sending outgoing emails, REDCap can utilize the Azure Communication Services API for sending emails as an alternative to using the REDCap web server's default methods that send emails. You first need to set up an account on the Microsoft/Azure website https://learn.microsoft.com/en-us/rest/api/communication/email, which will give you access to an Email API key that is connected to your Azure account. NOTE: You will need to create an account and generate the API token there in order to use it here in REDCap. Follow all instructions on the Microsoft/Azure website for obtaining and using the API token.
Azure Communication Services API Key


Azure Communication Services Endpoint
(e.g., https://my-resource.communication.azure.com/)


Limitations with Azure Communication Services: Due to limitations in the implementation of this API by Microsoft/Azure, this email-sending method is not able to display inline images in the body of emails, but any inline images will instead be represented as regular attachments. Additionally, the true sender’s email address and display name are not able to be displayed to the recipient in their email client, thus the recipient will only see the REDCap Universal 'From' Address as the sender with no corresponding display name.

Other system settings
Name of REDCap Administrator
REDCap Administrator for project(s)
Email Address of REDCap Administrator
Alternate URL for "Contact REDCap Admin" links on the left-hand menu of each project (optional)
By default (if the text box above is left blank), the "Contact REDCap Admin" links will open a pre-formatted email in the user's native email client. But if you enter a URL into the text box, the user's browser will navigate to that URL in a new tab after clicking the "Contact REDCap Admin" link. If you are using a ticket system, for example, to collect questions/issues from your users, you may enter the URL of the ticket system's page where new tickets can be submitted.
Name of Institution
Name of Organization at Institution (if applicable)
Name of grant to be cited (optional) - displayed when users export data
leave blank if none
URL for Custom Logo to be displayed at top of each project page (optional)
Max width: 650 pixels
Enable the Field Comment Log by default in new projects?
If enabled, any new project created will have the Field Comment Log initially enabled in the project. It can be disabled after the fact, if desired, in the Additional Customizations section of the project's Project Setup page.
Rate Limiter:
Page hit threshold for a single IP address
Maximum number of web requests per minute that are allowed from a single IP address when accessing a specific REDCap project (or a non-project page). If it is exceeded, that IP address will be permanently banned, thus preventing the user from accessing REDCap from that IP address again, and an administrator will be sent an email notification regarding this. This is to prevent bots or hackers from attempting an attack on the server.
requests per minute per IP
To disable the Rate Limiter, set the value to '0' or leave it blank.
Below you may optionally provide IP addresses or ranges to exclude from the Rate Limiter. This will be useful if performing security scans on your server, in which you can add the IP address of the scanning tool so that it does not get banned while performing scans.
IP address exceptions: You may enter IPv4 address ranges in either wildcard format with asterisks OR as a range with hyphen. IPv6 subnet masks may also be used. In addition to ranges, individual IP addresses may be used. All IP addresses and ranges must be separated by commas. Example: 1.2.3.*, 1.2.3.0-1.2.3.255, 21DA:00D3:0000:2F3B::/64
HTTP compression of web pages
This can make REDCap's pages load 2x-5x faster because it compresses the HTML output of each page.
Manually set the MySQL/MariaDB binlog_format setting for the REDCap database connection
WARNING: Do not change this from the default setting unless you know what you are doing and are intentional about this. Changing this to an incorrect value for your system configuration may cause catastrophic database issues.
Check For Identifiers - keywords
Keywords that will be used for querying which fields might be identifiers in the module Check For Identifiers. Please delimit each keyword using a comma, semi-colon, or line break.

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Example:
name, street, address, city, county, precinct, zip, postal, date, phone, fax, mail, ssn, social security, mrn, dob, dod, medical, record, id, age
Custom text to display at the top of the Help & FAQ page.
Custom message when creating/copying project
(Pop-up window of customized text that you wish your users to read to serve as notice/certification before creating or copying a project.)
Custom message when moving project to production
(Pop-up window of customized text that you wish your users to read to serve as notice/certification before moving a project to production.)