Best AI for coding / head-to-head

GLM 5.2 vs GPT-5.3-Codexfor coding

The verdict

Dead heat: 92 each

Same 18 coding tasks, marked blind by three rival labs. Tested 16 Aug 2026.

Where they differed most

The task — Typed debounce

Write a debounce function in TypeScript that preserves the argument types of the wrapped function, returns a function with a .cancel() method, and does not use 'any'. Explain in one sentence why the naive generic signature loses type information.

Here is the TypeScript debounce function:

```typescript
function debounce<A extends unknown[]>(
  func: (...args: A) => unknown,
  wait: number
): ((...args: A) => void) & { cancel: () => void } {
  let timeoutId: ReturnType<typeof setTimeout> | undefined;

  const debounced = ((...args: A): void => {
    if (timeoutId !== undefined) {
      clearTimeout(timeoutId);
    }
    timeoutId = setTimeout(() => func(...args), wait);
  }) as ((...args: A) => void) & { cancel: () => void };

  debounced.cancel = () => {
    if (timeoutId !== undefined)…
```ts
type Debounced<F extends (...args: unknown[]) => unknown> =
  ((...args: Parameters<F>) => void) & { cancel: () => void };

function debounce<F extends (...args: unknown[]) => unknown>(
  fn: F,
  waitMs: number
): Debounced<F> {
  let timer: ReturnType<typeof setTimeout> | undefined;

  const debounced = ((...args: Parameters<F>) => {
    if (timer !== undefined) {
      clearTimeout(timer);
    }
    timer = setTimeout(() => {
      fn(...args);
    }, waitMs);
  }) as Debounced<F>;

  debounced.cancel = () => {
    if (timer !== undefi…

Task by task

TaskGLM 5.2GPT-5.3-Codex
Duration parser89
Find the bug1010
SQL without window functions1010
Infinite useEffect109
Typed debounce810
Leftmost binary search1010
Security review99
Safe migration78
Fix the code not the test1010
Race condition99
Retry with backoff108
Recursive type109
Bash one-liner109
Explain and cost910
Regex with limits89
Callback to async109
Diagnose from a trace88
Idempotency910

Full receipts: GLM 5.2, GPT-5.3-Codex · judges claude-sonnet-5, gemini-3.1-pro-preview, gpt-5.6-terra

Questions people ask

Which is better for coding: GLM 5.2 or GPT-5.3-Codex?

They tied at 92/100 on our coding suite — for this job, pick on price or the product you already use.

How was this tested?

Both models answered the identical published 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 coding head-to-heads: GLM 5.2 vs GPT-5.6 Luna · GPT-5.3-Codex vs GPT-5.6 Luna · GLM 5.2 vs GPT-5.6 Sol · GPT-5.3-Codex vs GPT-5.6 Sol · GLM 5.2 vs GPT-5.6 Terra · GPT-5.3-Codex vs GPT-5.6 Terra

Full ranking: Best AI for coding · model pages: GLM 5.2, GPT-5.3-Codex