How Validation Rules Work
Validation rules are evaluated when a respondent submits their answer. If the answer doesn’t meet the validation criteria, an error message is displayed and the respondent must correct their input before proceeding. You can combine multiple validation rules using All are true or Any is true logic:- All are true: All rules must pass for the response to be valid
- Any is true: At least one rule must pass for the response to be valid
Available Validation Rules by Question Type
Free Text Questions
Free text questions support different validation rules based on the input type:Text Input Type
Email Input Type
Email input automatically validates email format. Additional rules available:- At least, At most (characters)
- Matches Regex Pattern, Is, Is not
- Contains, Does not contain
URL Input Type
URL input automatically validates URL format. Additional rules available:- At least, At most (characters)
- Matches Regex Pattern, Is, Is not
- Contains, Does not contain
Phone Input Type
Phone input automatically validates phone number format. Additional rules available:- At least, At most (characters)
- Matches Regex Pattern, Is, Is not
- Contains, Does not contain
Number Input Type
Multiple Choice (Multi-Select) Questions
Picture Selection Questions
Date Questions
Date values should be specified in YYYY-MM-DD format (e.g., 2025-01-15).
Matrix Questions
Ranking Questions
File Upload Questions
File size limits are configured separately in the question settings using the “Maximum file size” option.
Address Questions
Each address field (Address Line 1, Address Line 2, City, State, ZIP, Country) can have its own validation rules:- At least, At most (characters)
- Matches Regex Pattern
- Is, Is not
- Contains, Does not contain
Contact Info Questions
Each contact field can have specific validation rules: First Name, Last Name, Company:- At least, At most (characters)
- Matches Regex Pattern, Is, Is not
- Contains, Does not contain
Adding Validation Rules
1
Open the Question Settings
Click on the question you want to validate to open its settings panel.
2
Navigate to Validation Rules
Scroll down to find the “Validation Rules” section and click to expand it.
3
Add a Rule
Click the “Add rule” button to add a new validation rule.
4
Configure the Rule
Select the rule type from the dropdown and enter the required value (if applicable).
5
Set Logic (Optional)
If you have multiple rules, choose whether they should be combined with “All are true” or “Any is true” logic.
6
Save Your Survey
Click “Save” to apply the validation rules to your survey.
Error Messages
Formbricks automatically generates user-friendly error messages based on your validation rules. Error messages are displayed below the input field when validation fails. Example error messages:- “Must be at least 10 characters”
- “Must be a valid email address”
- “Please select at least 2 options”
- “Date must be after 2025-01-01”
Multi-Language Support
Validation rules work with multi-language surveys. Error messages are automatically displayed in the respondent’s selected language.Combining Multiple Rules
When using multiple validation rules: All are true: Use when all conditions must be met.- Example: Text must be at least 10 characters AND contain “@email.com”
- Example: Date is earlier than 2025-01-01 OR is later than 2025-12-31