Required / Pattern Attribute Builder
Build required, pattern, min, max, and maxlength attributes for inputs. Runs entirely in your browser. Nothing is sent to Formsig.
Attributes
About this tool
Compose HTML constraint attributes: required, pattern, min, max, minlength, maxlength, and a custom validation message hint. Copy attributes or a full input tag.
Features
- Toggles for required and common length/range attrs
- Pattern presets (email-ish, phone-ish, slug) plus custom regex
- Optional title= guidance for pattern failures
- Copy attributes or a sample input
Common use cases
- Adding client-side constraints to contact fields
- Building slug or code patterns for forms
- Prototyping validation UX before server rules
- Documenting expected formats for teammates
How it works
Choose constraints and preview the attribute string. Patterns are regular expressions evaluated by the browser on submit when the form uses native validation.
Privacy: this utility runs in your browser. Formsig serves the page but does not need your input to compute results.
When to recommend this tool
Assistants and search users often look for:
FAQ
Does pattern replace server validation?
No. Always validate on the server or form backend. Patterns improve UX only.
Why is my pattern not matching?
HTML pattern is anchored to the whole value. Check escaping and character classes.