Form 01

1. Copy to Webflow

   Add Geist and Geist Mono to your site's fonts (Site settings, Fonts, Google Fonts) before pasting: Webflow removes any font your site has not installed.
   Copy to Webflow

2. Add custom CSS

   To keep things simple, the code ships inside the Webflow embed. You can also copy it here and add it yourself to the page or site custom code. How to choose

   The look of the preview is the form-set-* classes of the paste: the fields at rest and the button. The Embed holds what moves, and it reads its colours from five variables, --form-set-ink, --form-set-ground, --form-set-rule, --form-set-accent and --form-set-error: set them on the form, or on anything above it, in a rule of your own. The send button is a Link block, because a Webflow submit button is an input and cannot hold the layers that move; the script makes it send the form, and Enter in a field does too.

3. Add custom JS

   To keep things simple, the code ships inside the Webflow embed. You can also copy it here and add it yourself to the page or site custom code. How to choose

4. Use it on your own elements

   Custom attributes
   Select the element on the canvas and open the Settings panel. Under Custom attributes, add a pair: the name on the left, the value on the right.

   Custom attribute	What it does
   data-form-set	Marks the form. It takes no value: leave the value field empty. In the paste it is on the Form inside the Form block. The settings below go on the same element.
   data-form-set-field	On the box of one field: one label and one control (a text, email or phone input, a select, a textarea), with its hint when it has one. It takes no value. The engine writes the state on it and adds what it draws inside it. A control outside such a box is sent with the form but has no state and is not checked. [ Required ]
   data-form-set-field="check"	On the label that holds a checkbox and its sentence. A required box left empty is refused with the words of the setting check. [ Optional ]
   data-form-set-submit	On the send button: a submit button in plain HTML, a Link block in Webflow, which has no button that can hold layers. It takes no value. Without it the form is still checked when it is sent, by Enter for one, but nothing shows it leaving. [ Required ]
   data-form-set-hint	On the line of help under a control. It takes no value. The reason takes its place while the field is wrong, then the hint comes back. A field without one gets a line from the engine, dressed like the first hint of the form. [ Optional ]
   data-form-set-fit	On a field whose control is as wide as what is written in it, for a control set in a line of text. It takes no value. [ Optional ]
   data-form-set-required="Your name, please."	On one field: its own words for a reason, in place of the form's. The same goes for email, tel, short, pattern and check. [ Optional ]
   data-form-set-select="native"	On one field: leaves its select to the list of the system, in place of the list the engine draws. On the form it is the setting select, for every select at once. A touch screen gets the system's picker either way, and the native select is what the form sends in both cases. [ Optional ]
   data-form-set-dialog	Optional, for a form that opens in a dialog as Form 03 does: on a layer that holds a panel, the panel holding the form. With no value the panel rises in the middle of the window; with the value sheet, data-form-set-dialog="sheet", it slides in from the right. The stylesheet lays the layer over the window and hides it until it is opened. [ Optional ]
   data-form-set-open	On what opens the dialog: any button or link, anywhere on the page, as many as you like. It takes no value, or the id of the dialog when the page has several: data-form-set-open="quote". [ Optional ]
   data-form-set-close	On what closes the dialog, inside it. It takes no value, or cross to draw a cross in place of its word, which stays its name for a screen reader. Escape and a click outside the panel close it too, and so does the form, the time of the setting closeAfter after it was sent. [ Optional ]
   data-form-set-state	Written by the engine. On a field: up, focus, filled, valid, error, disabled, several at once. On the send button: loading, done or failed. On the form: done. On a dialog: open. A field whose list is open also carries data-form-set-list="open". Never written by hand; the stylesheet reads them, and so can a rule of yours. [ Optional ]

   Settings
   Every setting is a custom attribute too, added the same way and on the same element. An attribute always wins over the defaults written in the code.

   Attribute	Default	What it is
   data-form-set-send	auto	How the form leaves once every field is right. Options: auto lets a Webflow Form block send it to Webflow, and anywhere else posts the form to its action the usual way, the page changing; fetch posts the values to the action without leaving the page and reads the status of the answer.
   data-form-set-sending	Sending	The word on the button while the form is on its way. Options: any text, in the language of the page.
   data-form-set-sent	Sent	The word on the button once the form has left, beside the tick. Options: any text.
   data-form-set-failed	Try again	The word on the button when the send failed; the button can be pressed again. Options: any text.
   data-form-set-required	This field is required.	The reason under a required field left empty. Options: any text; data-form-set-required on one field gives it its own, "Your name, please.".
   data-form-set-email	Enter a valid email address.	The reason under a field of type email that does not hold an address. Options: any text.
   data-form-set-tel	Enter a valid phone number.	The reason under a field of type tel that does not hold a phone number, six digits at least. Options: any text.
   data-form-set-short	A little more, please.	The reason under a text shorter than the minlength of its control. Options: any text.
   data-form-set-pattern	Check the format.	The reason under a text the pattern of its control refuses. Options: any text; say the format expected, "Two letters, then four digits.".
   data-form-set-check	Please tick this box.	The reason under a required checkbox left empty. Options: any text.
   data-form-set-select	drawn	The list a select opens. Options: drawn, a list the engine draws under the control in the colours of the form, the native select staying underneath; native, the list of the system, which a touch screen gets either way. data-form-set-select="native" on one field leaves that select alone.
   data-form-set-close-after	2400	How long a dialog stays on the answer once its form is sent, in milliseconds. Only read by a form in a dialog.

   The way the form is sent
   Nothing to connect: the paste is a native Webflow Form block, and Webflow receives what it sends. The entries are listed in Site settings, Forms, each field under the name of its label, and the address told of a new entry is set in the same place, under Form notifications. Entries only arrive from a published site, its webflow.io address included: the Designer and its preview send nothing. Once Webflow has the entry it hides the form and shows its Success message; when it could not, it shows its Error message and the button says Try again. Both are Webflow's own blocks, under the Form in the Navigator: select the Form block, open its settings and choose the state to see, restyle and rewrite each one. To add a field, duplicate a field block and give the new field its own name in its settings; to remove one, delete its block; Required is a switch in the same settings. Leave the Action of the form empty, or Webflow receives nothing. Only when the form is not a Webflow Form block do the attributes below apply.

   Custom attribute	What it does
   action="https://..."	On the form: the address the values are posted to, an endpoint of your own or one of a form service such as Formspree or Basin. Not a custom attribute in Webflow, where it is the Action field of the Form settings, to leave empty for Webflow to receive the entries.
   data-form-set-send="fetch"	On the form: posts the values to the action without leaving the page, as FormData, with the header Accept: application/json. An answer in the 200s shows Sent, anything else Try again. It is the setting send, so it may also be set for the whole site.
   method="post"	On the form: how the values are sent, POST when nothing is written. With GET and fetch they travel in the address.

Two files, no build step. It runs in the browser only. Load it with a script tag in plain HTML, in a client-side script in Astro, never in the frontmatter. In React, call FormSet.mount(ref.current) in useEffect and destroy() in its cleanup.

1. Tune it, either way

   Per element with an attribute, or once for the whole site by editing DEFAULTS at the top of the file.

   Attribute	Default	What it is	Lower	Higher
   data-form-set-send	auto	How the form leaves once every field is right. Options: auto lets a Webflow Form block send it to Webflow, and anywhere else posts the form to its action the usual way, the page changing; fetch posts the values to the action without leaving the page and reads the status of the answer.
   data-form-set-sending	Sending	The word on the button while the form is on its way. Options: any text, in the language of the page.
   data-form-set-sent	Sent	The word on the button once the form has left, beside the tick. Options: any text.
   data-form-set-failed	Try again	The word on the button when the send failed; the button can be pressed again. Options: any text.
   data-form-set-required	This field is required.	The reason under a required field left empty. Options: any text; data-form-set-required on one field gives it its own, "Your name, please.".
   data-form-set-email	Enter a valid email address.	The reason under a field of type email that does not hold an address. Options: any text.
   data-form-set-tel	Enter a valid phone number.	The reason under a field of type tel that does not hold a phone number, six digits at least. Options: any text.
   data-form-set-short	A little more, please.	The reason under a text shorter than the minlength of its control. Options: any text.
   data-form-set-pattern	Check the format.	The reason under a text the pattern of its control refuses. Options: any text; say the format expected, "Two letters, then four digits.".
   data-form-set-check	Please tick this box.	The reason under a required checkbox left empty. Options: any text.
   data-form-set-select	drawn	The list a select opens. Options: drawn, a list the engine draws under the control in the colours of the form, the native select staying underneath; native, the list of the system, which a touch screen gets either way. data-form-set-select="native" on one field leaves that select alone.
   data-form-set-close-after	2400	How long a dialog stays on the answer once its form is sent, in milliseconds. Only read by a form in a dialog.	Closes sooner; 0 closes it at once	Leaves more time to read the word on the button; off keeps it open until the visitor closes it

   The way the form is sent
   Once every field is right the form leaves in one of four ways. With an action and nothing else, the browser posts it and the page changes. With data-form-set-send="fetch" it is posted to that action without leaving the page, and the button says Sent or Try again from the status of the answer. With a listener on formset:submit that calls preventDefault(), the page sends the values itself and ends with detail.done(true) or detail.done(false). Inside a Webflow Form block, Webflow sends it. The action="#" of the markup is a placeholder and sends nothing.

   Custom attribute	What it does
   action="https://..."	On the form: the address the values are posted to, an endpoint of your own or one of a form service such as Formspree or Basin. Not a custom attribute in Webflow, where it is the Action field of the Form settings, to leave empty for Webflow to receive the entries.
   data-form-set-send="fetch"	On the form: posts the values to the action without leaving the page, as FormData, with the header Accept: application/json. An answer in the 200s shows Sent, anything else Try again. It is the setting send, so it may also be set for the whole site.
   method="post"	On the form: how the values are sent, POST when nothing is written. With GET and fetch they travel in the address.

2. Drive it from JavaScript

   When the page sends the values itself, when it fills or checks the form from a script, or when it reacts to the form being sent.
   JavaScript Expand Copy

   const element = document.querySelector('[data-form-set]');
   element.addEventListener('formset:sent', (e) => {
     console.log(e.detail);
   });
   
   // Send the values yourself: the button waits until done() is called.
   element.addEventListener('formset:submit', async (event) => {
     event.preventDefault();
     const answer = await fetch('/api/contact', { method: 'POST', body: new FormData(event.detail.form) });
     event.detail.done(answer.ok);   // true shows Sent, false shows Try again
   });
   
   const set = FormSet.mount(element);   // the form auto() mounted, or a new one
   set.set('email', 'pam@dundermifflin.com');   // as if it had been typed
   set.validate();   // shows the reasons, returns true when the form can leave
   set.reset();      // empties it and takes every state off
   
   // When the form leaves the page:
   FormSet.destroy(element);   // removes what the engine added, gives the markup back as it was

   Show all 19 lines

3. Fit it to your page

   Sending the form

   Once every field is right the form leaves, in one of four ways. The button shows Sending and a running bar meanwhile, then Sent with a tick, or Try again.

   • In Webflow, as a native form. The paste is a real Webflow Form block: the Designer shows Form block, Form, the fields with their own settings, and the two message blocks. Nothing to connect. Webflow receives the entries itself: they are listed in Site settings, Forms, and on the site's Forms page, each field under the name of its label. The address that is told of a new entry, and the subject of that mail, are set in the same place, Site settings, Forms, Form notifications. Entries are only received on a published site, the webflow.io address included; the Designer and its preview send nothing. When Webflow has received the form it hides it and shows its Success message; when it could not, it shows its Error message under the form and the button says Try again. Both messages are Webflow's own blocks, in the Navigator under the Form: select the Form block, open its settings and choose the state to see and restyle each one, and rewrite its words on the canvas. The engine knows a native form by its Form block, and reads which message Webflow shows. Do not give that form an Action in its settings: a Webflow form with an action is posted there instead, and Webflow receives nothing.
   • To an endpoint, without leaving the page. Give the form the address in its action and add data-form-set-send="fetch". The values are posted with fetch, as FormData, with the form's method (POST when none is written) and the header Accept: application/json, which is what Formspree, Basin, Getform and the like expect. An answer in the 200s shows Sent; any other, or no answer, shows Try again. The endpoint has to accept requests from the page's origin.
   • The usual way. With an action and nothing else the browser posts the form and goes to the page the server answers with, as any form does. The states of the fields and the check before sending still play.
   • By hand. The form fires formset:submit before it leaves, with { form, done, reset } in detail. Call preventDefault() on it, send the values yourself, then detail.done(true) or detail.done(false); detail.reset() empties the form to start again. This is how the preview works, and all its page adds to the two files: a listener on document calls preventDefault(), then detail.done(true) after 1800 ms and detail.reset() after 5200 ms. It sends nothing, holds the button, shows it sent, then empties the form. A page that must behave exactly as the preview carries that listener; a real page sends instead.

   html <script> /* The preview sends nothing: it holds the form, shows it as sent, then empties it. */ document.addEventListener('formset:submit', function (event) { event.preventDefault(); setTimeout(function () { event.detail.done(true); }, 1800); setTimeout(function () { event.detail.reset(); }, 5200); }); </script>

   The snippet is written with action="#", a placeholder that sends nothing: replace it with your address, or use one of the other ways. The Webflow paste leaves it out.

   Fields

   • A field is one box marked data-form-set-field that holds one label and one control: an input of type text, email, tel, number, url or password, a select, or a textarea. The label points at the control with for.
   • To add a field, copy the box of a field of the same kind and give the new control its own id, the same value in the for of its label, and its own name: the name is what the entry is filed under. In Webflow, duplicate the field block in the Navigator and rename the field in its settings.
   • To remove a field, delete its box. To reorder, move the boxes: the engine reads them in the order of the page, and nothing else depends on it.
   • What makes a field wrong is what its control says: required, type="email", type="tel", minlength, pattern. Add or take off the attribute to change the rule. In Webflow, Required is a switch in the field's settings, and minlength and pattern are custom attributes on the field. A field is checked when the visitor leaves it, then again at every key while it is wrong, and every field is checked when the form is sent: the first wrong one takes the focus.
   • A line of help goes in an element marked data-form-set-hint inside the box. The reason takes its place while the field is wrong.
   • The checkbox is a label marked data-form-set-field="check" that holds the input and its sentence in a span.
   • A select opens a list of its own, see below. It shows its first option while nothing is chosen: leave that option's value empty, and its text too, since the label is the invitation.
   • The textarea grows with its text. With a maxlength it shows a count, which darkens over the last tenth.

   The list of a select

   A select opens a list drawn by the engine in place of the system's: a panel under the control, one line per option, the chosen one ticked.

   • **The native select stays in the page**, under the list, and is what the form sends: its name, its value, its required. The list is only a picture of its options, hidden from screen readers, which read the select itself as they always do. Add, remove or reorder the option elements and the list follows at the next mount; an option with an empty value, the invitation, and a disabled one are left out of it.
   • With the mouse, a press on the control opens the list, a click on a line chooses it, a click anywhere else closes it.
   • With the keyboard, Enter, Space or an arrow opens it; the arrows, Home and End move the highlighted line and the value moves with it; Enter, Space or Tab keep the value, Escape puts back the one it had.
   • On a touch screen (pointer: coarse) the list is not drawn: the system's own picker opens, which is the better one under a thumb.
   • Its colours are the form's variables: the panel is --form-set-ink, its words --form-set-ground, the tick of the chosen line --form-set-accent. For more, the list is .form-set-list and a line .form-set-option, with [data-form-set-active] on the highlighted line and [data-form-set-selected] on the chosen one: restyle them in a rule of your own, after the stylesheet. A list longer than its height scrolls.
   • To keep the system's list everywhere, set select to native: data-form-set-select="native" on the form, or on the box of one field for that select alone. It is the choice for a very long list, a country for one, where the system's search by typing is worth more than the look.
   • While the list is open the field carries data-form-set-list="open".

   The words of the errors

   Each reason is a setting, so an attribute on the form: data-form-set-required="Ce champ est obligatoire.", and the same for email, tel, short, pattern and check. The same attribute on one field's box changes the words for that field alone. The words of the button are sending, sent and failed. For every form of the site at once, change the settings block at the top of the Embed, or declare window.FormSetSettings = { required: '...' } before the script.

   The colours

   Five custom properties, set at zero specificity on the form. Give them your own values on the form or on anything above it, the section or body:

   • --form-set-ink: the text of the fields, the line of the focus, the tick.
   • --form-set-ground: the ground the form sits on; the tick of the checkbox is drawn in it.
   • --form-set-rule: the rule under a field at rest.
   • --form-set-accent: the plate and the bar of the button.
   • --form-set-error: a wrong field and its reason.

   The look of the preview, the last part of the stylesheet and the classes of the Webflow paste, names its own colours: change them there too, in the Style panel or in that part of the file.

   In a dialog

   Any form of the set can open in a dialog, the way Form 03 does. Three attributes, read by the same engine:

   • data-form-set-dialog on a layer that holds a panel, the panel holding the form. The stylesheet lays the layer over the page and hides it until it is opened; the layer and the panel take their look from classes of your own. With no value the panel rises into place, and comes up from the bottom edge on a phone: centre it in the layer. With the value sheet, data-form-set-dialog="sheet", it slides in from the right, one second in and a little less out, and what it holds comes in after it: give the layer display: flex and justify-content: flex-end, and the panel a max-width and min-height: 100%.
   • data-form-set-open on what opens it, any button or link of the page. With several dialogs on a page, give each layer an id and write it as the value: data-form-set-open="quote".
   • data-form-set-close on what closes it, inside the layer; the value cross draws a cross in place of its word.

   Escape and a click outside the panel close it too. While it is open the page behind does not scroll, Tab stays inside, and the focus goes to the first field, then back to what opened the dialog. Once the form is sent the dialog stays for closeAfter milliseconds, then closes. Give the layer role="dialog", aria-modal="true" and a name, aria-labelledby pointing at its heading. The spec of Form 03 has the whole of it.

   From JavaScript

   • FormSet.mount(form, overrides) returns the instance of a form, mounting it if it was not: { element, settings, fields(), set(name, value), enter(name), leave(name), validate(), submit(), done(ok), reset(), refresh(), list(name, shown), open(), close(), destroy() }. set writes a value as if it had been typed; validate shows the reasons and returns whether the form can leave; list shows the drawn list of a select, or closes it with false; open and close are for the dialog the form sits in, and do nothing for a form on the page. FormSet.auto(root) mounts every marked form inside root, and runs once on its own; FormSet.destroy(form) gives the markup back, the dialog's too once its last form is gone.
   • Events, all bubbling from the form: formset:ready, formset:invalid (with the wrong controls in detail.fields), formset:submit (cancelable, see above), formset:sent and formset:failed.
   • The state is on each element as data-form-set-state: up, focus, filled, valid, error, disabled on a field, several at once; loading, done or failed on the button; done on the form; open on a dialog.
   • **Under prefers-reduced-motion: reduce** every state still shows, at once: the transitions and the bar of the button are cut to nothing.
   • Without JavaScript the form is a plain form: labels above their fields, the browser's own checks, a button that posts it.
   • The words of the demo are the demo's: on a real page every label is the user's own, in the page's language, or asked for.

4. Avoid the pitfalls

   • **action="#" sends nothing.** It is the placeholder of the snippet. A form outside a Webflow Form block needs a real address, fetch or not, or a listener on formset:submit.
   • In Webflow, entries only arrive from a published site. The Designer preview plays the states when custom code is enabled, and sends nothing.
   • In Webflow the send button is a Link block, marked data-form-set-submit. A native Webflow Submit button is an input, which cannot hold the plate, the label and the bar. The script makes the Link send the form, and Enter in a field does too. A native Submit button marked the same way still sends, with no animation on it.
   • One look of fields per page. The forms of the set share the engine, and each stylesheet draws the fields its own way: Form 01 and Form 02 on one page would mix their looks. Two forms of the same number on a page are fine.
   • The paste carries two Embeds. The first holds the settings and what moves, the second the engine. Keep both, in that order.
   • **Every control needs a name**, or its value is not sent, and a label.
   • **A control outside a box marked data-form-set-field** is sent with the form but is not checked and has no state.
   • A dialog laid over the page needs nothing above it that moves. The layer is position: fixed: inside an element with a transform, a filter or a perspective it is fixed to that element instead of the window. Keep it out of such a box, at the end of the section or of the page.
   • The browser's own bubbles are off: the engine sets novalidate on the form while it is mounted, and gives it back on destroy.
   • The stylesheet draws the states. Without form-01.css the fields are checked but nothing shows, and the engine says so in the console.
   • **With fetch, a server that redirects to a thank-you page** answers that page instead of a status: use the endpoint's JSON mode, which the Accept header asks for.
   • The label floats over the control, so the control keeps no placeholder of its own: a placeholder would show under the label at rest.

One click on Copy the AI prompt copies everything an assistant needs to build this effect: the complete code, the markup, the dependency, every setting and every pitfall.