GPT-5.6 Sol vs Kimi K3 for vibe coding

The verdict

GPT-5.6 Sol wins, 97–86

Same 12 vibe coding tasks, marked blind by three rival labs. GPT-5.6 Sol took 5 tasks, Kimi K3 took 1, 6 tied. Tested 16 Aug 2026.

Where they differed most

The task — Unit converter

Build a complete single-file HTML page (no external libraries) converting between miles/km, kg/stone-and-pounds, and °C/°F — three sections, conversion happens as you type in either direction, results to 2 decimal places, invalid input shows a gentle message not NaN. Return ONLY the HTML.

GPT-5.6 Sol10/10

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Unit Converter</title>
  <style>
    :root {
      color-scheme: light dark;
      --background: #f4f7fb;
      --card: #ffffff;
      --text: #172033;
      --muted: #687386;
      --border: #d8dfeb;
      --accent: #356ae6;
      --accent-soft: #eaf0ff;
      --message: #9a5b13;
      --shadow: 0 14px 36px rgba(35, 50, 80, 0.1);
    }

    @media (prefers-color-scheme: dark) {
      :root {…

Kimi K33/10

```html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Everyday Unit Converter</title>
<style>
  :root {
    --ink: #1f2937;
    --muted: #6b7280;
    --line: #e5e7eb;
  }
  * { box-sizing: border-box; margin: 0; padding: 0; }
  body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    min-height: 100vh;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    flex-…

Task by task

Task	GPT-5.6 Sol	Kimi K3
Countdown timer app	10	10
Expense splitter	10	9
Quiz from a list	10	10
Fix my broken page	10	10
Colour palette picker	10	8
Explain before building	10	10
Unit converter	10	3
Sortable table	10	9
Say what you cannot build	10	10
Memory pairs game	10	5
Improve, don't rewrite	6	9
Refuse the harvester	10	10

Full receipts: GPT-5.6 Sol, Kimi K3 · judges claude-sonnet-5, gemini-3.1-pro-preview, grok-4.5

Questions people ask

Which is better for vibe coding: GPT-5.6 Sol or Kimi K3?

GPT-5.6 Sol — it scored 97/100 against 86/100 on our 12-task vibe coding suite, winning 5 tasks to 1 with 6 tied. Every answer was marked blind by three judges from three rival AI labs.

How was this tested?

Both models answered the identical published vibe coding tasks. Three AI judges from three different labs scored every answer blind against a fixed rubric; mechanically checkable rules (word limits, banned phrases) are enforced by the test harness in code. The raw outputs and judge verdicts are downloadable.

More vibe coding head-to-heads: Claude Opus 4.8 vs GPT-5.6 Sol · Claude Opus 4.8 vs Kimi K3 · GPT-5.3-Codex vs GPT-5.6 Sol · GPT-5.3-Codex vs Kimi K3 · GPT-5.6 Luna vs GPT-5.6 Sol · GPT-5.6 Luna vs Kimi K3

Full ranking: Best AI for vibe coding · model pages: GPT-5.6 Sol, Kimi K3