System Prompt Editor

Edit the instructions the AI follows in every chat. Includes ready-made starters, a character count, and Save only when something changed.

Download the file Open full screen

One HTML file with the CSS and JavaScript inside. No library needed. MIT license.

Live preview

How to use it

Click Copy the code, or download the file.
Paste the CSS into your stylesheet, the HTML where you want the component, and the script before the closing body tag.
Change --accent at the top of the CSS to your brand color, then connect the events to your AI service.

What you get

Works in light and dark mode automatically
Keyboard friendly, with labels for screen readers
Fits phones, tablets and desktops
Respects the reduced motion setting
No framework, so it works with any stack

The code

<!DOCTYPE html>
<!--
  System Prompt Editor: a free AI UI component
  From 100 Free AI UI Components by MM Rahman Bappi, MIT license
  https://mmrahmanbappi.github.io/100-free-ai-ui-components/

  How to use: copy the CSS, HTML and JavaScript below into your page.
  Colors are CSS variables at the top. Change --accent to match your brand.
  Light and dark themes follow the visitor's system setting, or set
  data-theme="dark" or data-theme="light" on the html element.
-->
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>System Prompt Editor | Free AI UI Component</title>
<meta name="description" content="Edit the instructions the AI follows in every chat. Includes ready-made starters, a character count, and Save only when something changed.">
<meta name="robots" content="noindex, follow">
<style>
:root{
  --accent:#5b5bd6; --accent-ink:#fff; --accent-soft:#ececfc;
  --bg:#f7f7f8; --surface:#fff; --surface-2:#f1f1f4; --ink:#17171c; --text:#3a3a44; --muted:#6c6c78;
  --line:#e3e3e8; --good:#15803d; --warn:#b45309; --bad:#c62828;
  --radius:14px; --shadow:0 1px 2px rgba(20,20,30,.06),0 8px 24px -12px rgba(20,20,30,.18);
  --font:system-ui,-apple-system,"Segoe UI",Roboto,Ubuntu,sans-serif; --mono:ui-monospace,"Cascadia Code",Menlo,Consolas,monospace;
}
@media (prefers-color-scheme:dark){:root:not([data-theme=light]){
  --accent:#8b8bff; --accent-ink:#0f0f16; --accent-soft:#25254a;
  --bg:#0f0f13; --surface:#18181f; --surface-2:#212129; --ink:#f3f3f6; --text:#d4d4dc; --muted:#9a9aa8;
  --line:#2c2c36; --good:#4ade80; --warn:#fbbf24; --bad:#f87171; --shadow:0 1px 2px rgba(0,0,0,.4),0 10px 30px -12px rgba(0,0,0,.6);
}}
:root[data-theme=dark]{
  --accent:#8b8bff; --accent-ink:#0f0f16; --accent-soft:#25254a;
  --bg:#0f0f13; --surface:#18181f; --surface-2:#212129; --ink:#f3f3f6; --text:#d4d4dc; --muted:#9a9aa8;
  --line:#2c2c36; --good:#4ade80; --warn:#fbbf24; --bad:#f87171; --shadow:0 1px 2px rgba(0,0,0,.4),0 10px 30px -12px rgba(0,0,0,.6);
}
*{box-sizing:border-box}
html,body{margin:0}
body{min-height:100vh;display:grid;grid-template-columns:minmax(0,1fr);place-items:center;padding:24px;background:var(--bg);color:var(--text);font:15px/1.5 var(--font);-webkit-font-smoothing:antialiased}
button,input,textarea,select{font:inherit;color:inherit}
:focus-visible{outline:2px solid var(--accent);outline-offset:2px}
[hidden]{display:none!important}
.sr{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
@media (prefers-reduced-motion:reduce){*,*::before,*::after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition:none!important}}
/* ---- component ---- */
.wrap{width:min(100%,580px);display:flex;flex-direction:column;gap:14px}
.card{background:var(--surface);border:1px solid var(--line);border-radius:var(--radius);box-shadow:var(--shadow);padding:18px 20px}
.card h2{font-size:15.5px;margin:0 0 4px;color:var(--ink)}
.muted{color:var(--muted);font-size:13px}
.num{font-variant-numeric:tabular-nums}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:6px;border:1px solid var(--line);background:var(--surface);color:var(--ink);border-radius:10px;padding:8px 14px;font-size:14px;font-weight:600;cursor:pointer}
.btn:hover{border-color:var(--accent)}.btn.pri{background:var(--accent);border-color:var(--accent);color:var(--accent-ink)}.btn:disabled{opacity:.45;cursor:not-allowed}
.btn.danger{color:var(--bad)}.btn.danger:hover{border-color:var(--bad)}
.tg{width:40px;height:23px;border-radius:99px;background:var(--line);position:relative;flex:none;border:0;cursor:pointer;padding:0;transition:background .15s}
.tg::after{content:"";position:absolute;top:3px;left:3px;width:17px;height:17px;border-radius:50%;background:#fff;transition:left .15s;box-shadow:0 1px 2px rgba(0,0,0,.2)}
.tg[aria-checked=true]{background:var(--accent)}.tg[aria-checked=true]::after{left:20px}
.row{display:flex;justify-content:space-between;align-items:center;gap:14px;padding:12px 0;border-top:1px solid var(--line)}
.row:first-of-type{border-top:0}
.row b{display:block;color:var(--ink);font-size:14px;font-weight:600}.row small{display:block;color:var(--muted);font-size:12.5px;margin-top:1px}
.seg{display:flex;background:var(--surface-2);border-radius:12px;padding:4px;gap:4px}
.seg button{flex:1;border:0;background:none;padding:8px 10px;border-radius:9px;font-size:14px;color:var(--muted);cursor:pointer;font-weight:500}
.seg button[aria-checked=true]{background:var(--surface);color:var(--ink);font-weight:700;box-shadow:0 1px 3px rgba(0,0,0,.12)}
.sample{margin:14px 0 0;padding:12px 14px;border-radius:12px;background:var(--surface-2);font-size:14px;line-height:1.6;color:var(--text);transition:opacity .2s}
.sample small{display:block;color:var(--muted);font-size:12px;margin-bottom:4px}
.wrap{width:min(100%,640px)}
.hd{display:flex;justify-content:space-between;align-items:center;gap:10px;flex-wrap:wrap;margin-bottom:10px}
select{border:1px solid var(--line);border-radius:10px;padding:7px 10px;background:var(--surface);color:var(--ink);font-size:13.5px}
textarea{width:100%;min-height:150px;resize:vertical;border:1px solid var(--line);border-radius:12px;padding:12px;background:var(--surface-2);color:var(--ink);font:13.5px/1.6 var(--mono)}
textarea:focus{outline:0;border-color:var(--accent);background:var(--surface)}
.ft{display:flex;justify-content:space-between;align-items:center;gap:10px;margin-top:10px;flex-wrap:wrap}
.ft div{display:flex;gap:8px}
.dirty{color:var(--warn);font-weight:600}.saved{color:var(--good);font-weight:600}
</style>
</head>
<body>
<div class="wrap"><div class="card">
  <div class="hd"><div><h2>Custom instructions</h2><p class="muted" style="margin:0">The AI follows these in every new chat.</p></div>
    <label class="sr" for="tpl">Start from a template</label><select id="tpl"><option value="">Start from a template</option><option value="tutor">Patient tutor</option><option value="editor">Strict editor</option><option value="brief">Short answers</option></select></div>
  <label class="sr" for="ta">Instructions</label><textarea id="ta" maxlength="1500" spellcheck="true"></textarea>
  <div class="ft"><span class="muted num" id="st" role="status" aria-live="polite"></span><div><button class="btn" type="button" id="rs">Reset</button><button class="btn pri" type="button" id="sv" disabled>Save</button></div></div>
</div></div>
<script>
// Demo helper: add ?theme=dark or ?theme=light to the address to preview a theme.
(function(){var t=new URLSearchParams(location.search).get('theme');if(t)document.documentElement.dataset.theme=t;})();
var T={tutor:'You are a patient tutor. Explain ideas step by step using simple words and one short example. Ask a question at the end to check understanding.',
editor:'You are a strict editor. Point out unclear sentences, repeated words and weak verbs. Suggest a shorter version of each paragraph.',
brief:'Answer in three sentences or fewer. Use plain words. Skip greetings and summaries.'};
var saved='Be friendly and clear. Use short paragraphs. When you are not sure, say so.',ta=document.getElementById('ta'),st=document.getElementById('st'),sv=document.getElementById('sv'),tpl=document.getElementById('tpl');
function showStatus(msg,cls){var n=ta.value.length;st.innerHTML=n.toLocaleString()+' / 1,500'+(msg?' <span class="'+cls+'">'+msg+'</span>':'');}
function check(){var dirty=ta.value!==saved;sv.disabled=!dirty;showStatus(dirty?'Unsaved changes':'','dirty');}
ta.addEventListener('input',check);
tpl.addEventListener('change',function(){if(!tpl.value)return;ta.value=T[tpl.value];tpl.value='';check();ta.focus();});
document.getElementById('rs').addEventListener('click',function(){ta.value=saved;check();});
sv.addEventListener('click',function(){saved=ta.value;sv.disabled=true;showStatus('Saved','saved');});
window.addEventListener('beforeunload',function(e){if(ta.value!==saved){e.preventDefault();e.returnValue='';}});
ta.value=saved;check();
</script>
</body>
</html>

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Creativity Slider
A slider for the model temperature with plain labels from Precise to Creative, a live value, and a sample line that shows the effect.
Answer Length Control
A three-way switch for short, medium or long answers, with a preview that shows how much text each choice gives.
Tone Selector
Pick how the AI should sound: friendly, professional, casual or direct. A sample reply updates so people can hear the difference.
Feature Toggles
A settings list of switches for AI features like web search, memory and code running, each with a short explanation.
Assistant Persona Cards
Cards for different assistant roles, like tutor, editor or coach. Picking one changes how the assistant greets you.

System Prompt Editor

How to use it

What you get

The code

More model and settings components

Model Selection Cards

Creativity Slider

Answer Length Control

Tone Selector

Feature Toggles

Assistant Persona Cards