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Every control changes the real MTCaptcha widget and the code that ships it. Start from our defaults, then make it yours.

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Palette

Capabilities

Modern MiniCompact, one line

InvisibleNo challenge for humans

AccessibilityWCAG 2.1 AAA, audio

Language

Explore 20 brand templates Banking, health, gaming, luxury and more

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', '', ].join('\n'); } function paintCode(mount, src) { var n = src.split('\n').length, nums = ''; for (var i = 1; i <= n; i++) nums += i + '\n'; mount.innerHTML = '' + '

' + highlight(src) + '

'; } /* ---------- render ---------- */ var patched = false; function patchRemove() { if (patched || !window.mtcaptcha || !window.mtcaptcha.remove) return; var orig = window.mtcaptcha.remove.bind(window.mtcaptcha); window.mtcaptcha.remove = function (id) { try { return orig(id); } catch (e) { return undefined; } }; patched = true; } setInterval(patchRemove, 200); var timer = null; function rerender() { clearTimeout(timer); timer = setTimeout(function () { patchRemove(); /* By id, never by the bare 'mtcaptcha'. The vendor resolves a missing or unknown id to `domId || "class:mtcaptcha"`, which on a page carrying a second widget - the contact form's, on every Use Cases page - is the wrong one as often as the right one: this would tear down and rebuild the contact captcha, discarding a token a visitor had already solved. */ if (window.mtcaptcha && window.mtcaptcha.remove) window.mtcaptcha.remove('mtcaptcha-demo'); CFG.renderQueue.push('mtcaptcha-demo'); fitWidget(); }, 280); } /* The widget's own stylesheet floors it at 285px wide and clips the rest, so on a phone narrower than that it is scaled down instead of losing its right edge. Everywhere there is room this is a no-op: the factor stays at 1. The slot's height is set from the scaled height because the widget is transformed, and a transform does not affect layout: without this the card would keep reserving the unscaled height and leave a gap above Sign in. */ var WIDGET_MIN_W = 285; function fitWidget() { var slot = document.querySelector('.mtc-slot'); if (!slot) return; var holder = slot.querySelector('.mtcaptcha'); var avail = slot.clientWidth; if (!holder || !avail) return; if (avail >= WIDGET_MIN_W) { slot.classList.remove('is-scaled'); slot.style.removeProperty('--mtc-fit'); slot.style.height = ''; return; } /* Width and transform go on first, so offsetHeight is the height the widget actually takes at 285px rather than at its squeezed width. */ slot.classList.add('is-scaled'); var f = avail / WIDGET_MIN_W; slot.style.setProperty('--mtc-fit', String(f)); var h = holder.offsetHeight; slot.style.height = h ? Math.ceil(h * f) + 'px' : ''; } window.addEventListener('resize', fitWidget); /* Watch the card, not the slot: fitWidget sets the slot's height, so observing the slot would feed its own writes back in. Only a real change in available width does anything. */ if (window.ResizeObserver) { var cardEl = document.querySelector('.mtc-card'); var lastW = 0; if (cardEl) { new ResizeObserver(function () { var w = cardEl.clientWidth; if (w === lastW) return; lastW = w; fitWidget(); }).observe(cardEl); } } /* The console's controls are bordered with --line, an alpha of the ink rather than a tinted hex, which is what makes them read as subtle at any background. The mock's fields use the same two values so its borders match the language select exactly, and stay subtle under every palette instead of picking up that palette's tint. */ function subtleLine(th) { return th.dark ? 'rgba(255, 255, 255, 0.09)' : 'rgba(4, 10, 26, 0.09)'; } /* What a visitor types is the console's --ink, not the palette's. Every palette carries its own ink, tuned to its own hues - Sandstone's is a warm #2f2617, Ocean's a blue-black - and switching palette moved the field text off the colour the language select uses. Read the token rather than repeating its value, so it cannot drift from global.css. */ function siteInk() { var v = getComputedStyle(document.documentElement).getPropertyValue('--ink').trim(); return v || (siteIsDark() ? '#f4f6ff' : '#040a1a'); } /* Alpha rather than a second hex per palette, so a lightened colour cannot drift away from the ink it was lightened from. */ function fade(hex, a) { var c = toRgb(hex); return 'rgba(' + c[0] + ', ' + c[1] + ', ' + c[2] + ', ' + a + ')'; } function subtleLineStrong(th) { return th.dark ? 'rgba(255, 255, 255, 0.16)' : 'rgba(4, 10, 26, 0.14)'; } /* sRGB relative luminance and contrast ratio, WCAG 2.x. */ function toRgb(hex) { var h = hex.replace('#', ''); if (h.length === 3) h = h[0] + h[0] + h[1] + h[1] + h[2] + h[2]; var n = parseInt(h, 16); return [(n >> 16) & 255, (n >> 8) & 255, n & 255]; } function lum(c) { var a = c.map(function (v) { v /= 255; return v <= 0.03928 ? v / 12.92 : Math.pow((v + 0.055) / 1.055, 2.4); }); return 0.2126 * a[0] + 0.7152 * a[1] + 0.0722 * a[2]; } function contrast(a, b) { var l1 = lum(a), l2 = lum(b); return l1 < l2 ? (l2 + 0.05) / (l1 + 0.05) : (l1 + 0.05) / (l2 + 0.05); } function mix(fg, bg, a) { return [0, 1, 2].map(function (i) { return Math.round(fg[i] * a + bg[i] * (1 - a)); }); } /* The lightest `hex` can be drawn on `bg` while still clearing `target`. Contrast falls monotonically as the colour is mixed toward the background, so the smallest passing alpha is a plain bisection. A palette with no headroom left is returned untouched rather than darkened: this exists to lighten, and quietly strengthening a palette's own colour would be a different change than the one asked for. */ function lightestAA(hex, bgHex, target) { var fg = toRgb(hex), bg = toRgb(bgHex); if (contrast(fg, bg) < target) return hex; var lo = 0, hi = 1; for (var i = 0; i < 14; i++) { var mid = (lo + hi) / 2; if (contrast(mix(fg, bg, mid), bg) >= target) hi = mid; else lo = mid; } var c = mix(fg, bg, hi); return 'rgb(' + c[0] + ', ' + c[1] + ', ' + c[2] + ')'; } function styleFor(th) { var out = { cardColor: th.card, cardBorder: '1px solid ' + th.line, cardBorderRadius: '12px', inputBackgroundColor: th.inputBg, inputBorderColor: { byDefault: subtleLine(th), hover: subtleLineStrong(th), active: th.accent }, inputTextColor: siteInk(), /* The prompt is lighter than the text a visitor types, and lighter than the widget's own default, which is close enough to the typed colour to read as a pre-filled value. Ink at 38% over the field background lands well clear of both while still tracking the palette. */ placeHolderColor: fade(siteInk(), 0.38), /* "Privacy & Terms" and "Powered by MTCaptcha" are the widget's outer captions, and this is the only key that reaches them, so they lighten without touching the fields, the prompt or the card. Lightened to the limit rather than by a fixed amount. A single alpha cannot work here: the palettes' muted greys already sit between 4.7:1 and 8.1:1 on their own cards, so the same step that visibly lightens MTCaptcha's #4a5060 pushes Ocean's #5a7690 straight through the floor. Each palette is given the lightest caption it can afford instead. The floor is 3.6:1, which is BELOW normal-text AA, and that is a decision rather than an oversight - do not "fix" it back to 4.5 without asking. Both strings are small text: 12.32px for "Powered by MTCaptcha" and 10.72px for the legal block, well under the 18.66px that would let bold count as large, so AA would ask 4.5:1 of them. It was set there first and the captions were judged still too heavy. The two share one key, so the legal block - a pair of real links - could not be held at AA while only the caption lightened. 3.6 rather than lower because that is the AA floor for large text and the minimum WCAG asks of any UI component boundary, so the captions stay above the point where they stop reading as text at all. */ msgTextColor: lightestAA(th.muted, th.card, 3.6), buttonIconColor: a11y ? th.accent : th.muted, inputTextFont: FONT_STACK, msgTextFont: FONT_STACK, }; /* Outlined is the default here: every palette already gets a 1px card border from its own line colour. Only the gradient treatment adds anything on top. */ if (th.gradient) { out.cardBGGradient = 'linear-gradient(160deg, ' + th.card + ' 0%, ' + th.accentSoft + ' 100%)'; } return out; } function siteIsDark() { return document.documentElement.classList.contains('dark'); } /* Name and treatment belong to the brand; colours come from the mode. */ function resolve(entry) { return Object.assign({ name: entry.name, gradient: entry.gradient }, siteIsDark() ? entry.dark : entry.light); } function apply() { var th = resolve(THEMES[themeIx]), c = CTX[ctx]; /* Scoped to the demo container, never to . */ root.style.setProperty('--demo-page', th.page); root.style.setProperty('--demo-card', th.card); root.style.setProperty('--demo-line', th.line); root.style.setProperty('--demo-ink', th.ink); root.style.setProperty('--demo-field-ink', siteInk()); root.style.setProperty('--demo-muted', th.muted); root.style.setProperty('--demo-accent', th.accent); root.style.setProperty('--demo-on-accent', th.onAccent); root.style.setProperty('--demo-input-bg', th.inputBg); root.style.setProperty('--demo-input-line', subtleLine(th)); root.style.setProperty('--demo-shadow', th.dark ? '0 14px 40px rgba(0,0,0,0.5)' : '0 12px 34px rgba(6,10,24,0.08)'); $('mtc-addr').textContent = c.url; $('mtc-c-title').textContent = c.title; $('mtc-c-sub').textContent = c.sub; $('mtc-c-go').textContent = c.go; $('mtc-c-fields').innerHTML = c.fields.map(function (f, i) { return '' + f[0] + '' + ''; }).join(''); /* Invisible has nothing to render, which is the point. An empty gap reads as a broken widget, so it says so instead. */ $('mtc-inv-note').innerHTML = invisible ? '' : ''; $('mtc-a11y-note').innerHTML = a11y && !invisible ? '

' + S.a11yNote + '

' : ''; var cfg = { sitekey: '', lang: wlang }; /* No autoFadeOuterText on the dark palettes. It fades the widget's outer text out entirely, so "Privacy & Terms" and "Powered by MTCaptcha" went invisible against a dark card. msgTextColor already carries the dark palette's muted tone, which is the same token the form's own labels use, so the captions stay legible and match the rest of the card. */ if (th.dark) { cfg.theme = 'blackmoon'; } if (mini) cfg.widgetSize = 'mini'; if (invisible) cfg.lowFrictionInvisible = 'force-invisible'; cfg.customFonts = { fonts: [{ family: 'Poppins', url: FONT_URL, format: 'woff2' }], defaultFontFamily: FONT_STACK }; cfg.customStyle = styleFor(th); codeText = snippet(cfg); paintCode($('mtc-snippet'), codeText); CFG.lang = wlang; CFG.theme = th.dark ? 'blackmoon' : null; CFG.autoFadeOuterText = null; CFG.widgetSize = mini ? 'mini' : null; CFG.customFonts = cfg.customFonts; CFG.customStyle = cfg.customStyle; /* Deleted rather than nulled: the vendor reads the key's presence. */ if (TESTKEY) CFG.enableTestMode = TESTKEY; else delete CFG.enableTestMode; if (invisible) { CFG.testmode_lowFrictionInvisible = 'force-invisible'; CFG.lowFrictionInvisible = null; CFG.loadAnimation = 'false'; } else { CFG.testmode_lowFrictionInvisible = 'force-visible'; CFG.lowFrictionInvisible = 'force-visible'; CFG.loadAnimation = 'true'; } $('mtc-live').textContent = th.name + ', ' + ctx; rerender(); } /* ---------- controls ---------- */ var sw = $('mtc-swatches'); function chooseTheme(i) { themeIx = i; [].forEach.call(sw.children, function (x, j) { x.setAttribute('aria-checked', String(j === i)); x.tabIndex = j === i ? 0 : -1; }); apply(); } THEMES.forEach(function (th, i) { var b = document.createElement('button'); b.className = 'mtc-sw'; b.type = 'button'; b.setAttribute('role', 'radio'); b.setAttribute('aria-label', th.name); b.setAttribute('aria-checked', i === 0 ? 'true' : 'false'); b.tabIndex = i === 0 ? 0 : -1; var chip = resolve(th); b.style.background = 'linear-gradient(135deg,' + chip.page + ' 0 50%,' + chip.accent + ' 50% 100%)'; b.onclick = function () { chooseTheme(i); }; b.onkeydown = function (e) { var d = e.key === 'ArrowRight' ? 1 : e.key === 'ArrowLeft' ? -1 : 0; if (!d) return; e.preventDefault(); var n = (i + d + THEMES.length) % THEMES.length; chooseTheme(n); sw.children[n].focus(); }; sw.appendChild(b); }); var ctxBtns = [].slice.call(document.querySelectorAll('#mtc-ctxs [data-ctx]')); function pickCtx(i) { ctx = ctxBtns[i].getAttribute('data-ctx'); ctxBtns.forEach(function (x, j) { x.setAttribute('aria-checked', String(j === i)); x.tabIndex = j === i ? 0 : -1; }); apply(); } ctxBtns.forEach(function (b, i) { b.tabIndex = i === 0 ? 0 : -1; b.onclick = function () { pickCtx(i); }; b.onkeydown = function (e) { var d = e.key === 'ArrowRight' ? 1 : e.key === 'ArrowLeft' ? -1 : 0; if (!d) return; e.preventDefault(); var n = (i + d + ctxBtns.length) % ctxBtns.length; pickCtx(n); ctxBtns[n].focus(); }; }); function toggle(id, set) { var el = $(id); el.onclick = function () { var on = el.getAttribute('aria-checked') !== 'true'; el.setAttribute('aria-checked', String(on)); set(on); apply(); }; } toggle('mtc-t-mini', function (v) { mini = v; }); toggle('mtc-t-inv', function (v) { invisible = v; }); toggle('mtc-t-a11y', function (v) { a11y = v; }); Select($('mtc-lang-mount'), LANGS.map(function (l) { return { value: l[0], label: l[1] }; }), initialLang, 'mtc-g-lang', function (v) { wlang = v; apply(); }); var tabP = $('mtc-tab-preview'), tabC = $('mtc-tab-code'); function selectTab(which) { var p = which === 'preview'; tabP.setAttribute('aria-selected', String(p)); tabC.setAttribute('aria-selected', String(!p)); tabP.tabIndex = p ? 0 : -1; tabC.tabIndex = p ? -1 : 0; $('mtc-pane-preview').hidden = !p; $('mtc-pane-code').hidden = p; $('mtc-copy').hidden = p; $('mtc-addr').hidden = !p; } tabP.onclick = function () { selectTab('preview'); }; tabC.onclick = function () { selectTab('code'); }; [tabP, tabC].forEach(function (b) { b.onkeydown = function (e) { if (e.key !== 'ArrowRight' && e.key !== 'ArrowLeft') return; e.preventDefault(); var next = b === tabP ? tabC : tabP; selectTab(next === tabP ? 'preview' : 'code'); next.focus(); }; }); var copyBtn = $('mtc-copy'); copyBtn.onclick = function () { navigator.clipboard.writeText(codeText); copyBtn.textContent = copyBtn.getAttribute('data-copied'); setTimeout(function () { copyBtn.textContent = copyBtn.getAttribute('data-copy'); }, 1200); }; /* The site's theme toggle flips a class on , so an observer is the only signal available; there is no event to listen for. Guarded on tracksSite so an explicit palette choice survives a theme change. */ new MutationObserver(function () { [].forEach.call(sw.children, function (x, j) { var chip = resolve(THEMES[j]); x.style.background = 'linear-gradient(135deg,' + chip.page + ' 0 50%,' + chip.accent + ' 50% 100%)'; x.setAttribute('aria-label', THEMES[j].name); }); apply(); }).observe(document.documentElement, { attributes: true, attributeFilter: ['class'] }); selectTab('preview'); setTimeout(apply, 500); })(); })();

<html>
  <head>
    <!-- Configuration to construct the captcha widget. Sitekey is a Mandatory Parameter-->
    <script>
      var mtcaptchaConfig = {
        "sitekey": "<YOUR SITE KEY>"
       };
      (function(){var mt_service = document.createElement('script');mt_service.async = true;mt_service.src = 'https://service.mtcaptcha.com/mtcv1/client/mtcaptcha.min.js';(document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(mt_service);
      var mt_service2 = document.createElement('script');mt_service2.async = true;mt_service2.src = 'https://service2.mtcaptcha.com/mtcv1/client/mtcaptcha2.min.js';(document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(mt_service2);}) ();
    </script>
  </head>
  <body>
    <!-- MTCaptcha library by default looks for a DIV of class='mtcaptcha' to place the captcha widget -->
    <div class="mtcaptcha"></div>
  </body>
</html>