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GLM 5.3 Flash · Coding

GLM 5.3 Flash for coding: our test runs

GLM 5.3 Flash ran our 5 coding prompts in llmwise, through the same pipeline your messages take. Here's every reply as it came, whether it passed, what it cost and what it counts as on Pro, next to the other models.

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Based on 5 of our test runs on , through OpenRouter with the app's own prompt and settings. Updated .

Short answer

In our test runs on September 27, 2026, GLM 5.3 Flash passed 5 of 5 of our coding prompts (both hard ones): tied 1st of 15 models. Each reply counted as 1 message on Pro, where it has 60 a day, and cost $0.0003 to run on average.

Prompt by prompt

Each of the 5 coding prompts, and how GLM 5.3 Flash's reply did.

GLM 5.3 Flash on each coding prompt
PromptResultCostTime
Turn a title into a URL slugEverydayPassed: All 7 tests passed.$0.00012.6 s
Parse a duration like “1h 30m”EverydayPassed: All 10 tests passed.$0.00038.2 s
Merge overlapping intervalsEverydayPassed: All 7 tests passed.$0.00029.6 s
Evaluate an arithmetic expression, no evalHardPassed: All 15 tests passed.$0.000411.1 s
Parse CSV with quoted fieldsHardPassed: All 8 tests passed.$0.00038.4 s

Every coding reply from GLM 5.3 Flash

  1. Turn a title into a URL slug

    An everyday prompt: “Turn a title into a URL slug”, in full.

    Passed: All 7 tests passed.

    ```javascript
function slugify(title) {
  const normalized = title.normalize("NFD").replace(/[\u0300-\u036f]/g, "");
  return normalized
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, "-")
    .replace(/^-+|-+$/g, "");
}
```

    499 tokens in, 75 out · 2.6 s · $0.0001 · 1 message on Pro · answered by z-ai/glm-5.3-flash via GMICloud ·

  2. Parse a duration like “1h 30m”

    An everyday prompt: “Parse a duration like “1h 30m””, in full.

    Passed: All 10 tests passed.

    ```javascript
function parseDuration(text) {
  if (typeof text !== "string") return null;
  const m = text.match(/^\s*(?:(\d+)h\s*)?(?:(\d+)m\s*)?(?:(\d+)s\s*)?$/);
  if (!m || (m[1] === undefined && m[2] === undefined && m[3] === undefined)) {
    return null;
  }
  const [h = 0, mi = 0, s = 0] = m.slice(1).map((v) => (v === undefined ? 0 : Number(v)));
  return h * 3600 + mi * 60 + s;
}
```

    481 tokens in, 470 out (320 of them reasoning) · 8.2 s · $0.0003 · 1 message on Pro · answered by z-ai/glm-5.3-flash via Morph ·

  3. Merge overlapping intervals

    An everyday prompt: “Merge overlapping intervals”, in full.

    Passed: All 7 tests passed.

    ```javascript
function mergeIntervals(intervals) {
  // Sort a copy by start so the input array is left unchanged
  const sorted = [...intervals].sort((a, b) => a[0] - b[0]);

  const merged = [];
  for (const [start, end] of sorted) {
    const last = merged[merged.length - 1];
    // Merge when overlapping ([1,4] & [2,5]) or touching ([1,3] & [3,5])
    if (last && start <= last[1]) {
      last[1] = Math.max(last[1], end);
    } else {
      merged.push([start, end]);
    }
  }
  return merged;
}
```

Example: `mergeIntervals([[5, 7], [1, 3], [3, 5], [8, 10]])` → `[[1, 7], [8, 10]]`.

    463 tokens in, 287 out (82 of them reasoning) · 9.6 s · $0.0002 · 1 message on Pro · answered by z-ai/glm-5.3-flash via Wafer ·

  4. Evaluate an arithmetic expression, no eval

    A hard prompt: “Evaluate an arithmetic expression, no eval”, in full.

    Passed: All 15 tests passed.

    ```javascript
function evaluate(expression) {
  let i = 0;
  const s = expression;

  function skipSpaces() {
    while (i < s.length && s[i] === ' ') i++;
  }

  function parseExpr() {
    let value = parseTerm();
    for (;;) {
      skipSpaces();
      if (s[i] === '+') { i++; value += parseTerm(); }
      else if (s[i] === '-') { i++; value -= parseTerm(); }
      else return value;
    }
  }

  function parseTerm() {
    let value = parseUnary();
    for (;;) {
      skipSpaces();
      if (s[i] === '*') { i++; value *= parseUnary(); }
      else if (s[i] === '/') { i++; value /= parseUnary(); }
      else return value;
    }
  }

  function parseUnary() {
    skipSpaces();
    if (s[i] === '-') { i++; return -parseUnary(); }
    return parsePower();
  }

  function parsePower() {
    const base = parsePrimary();
    skipSpaces();
    if (s[i] === '^') {
      i++;
      return Math.pow(base, parseUnary()); // right-assoc, allows 2^-1
    }
    return base;
  }

  function parsePrimary() {
    skipSpaces();
    if (s[i] === '(') {
      i++;
      const value = parseExpr();
      skipSpaces();
      if (s[i] !== ')') throw new Error("Expected ')'");
      i++;
      return value;
    }
    const start = i;
    while (i < s.length && s[i] >= '0' && s[i] <= '9') i++;
    if (i < s.length && s[i] === '.') {
      i++;
      while (i < s.length && s[i] >= '0' && s[i] <= '9') i++;
    }
    if (i === start || (i === start + 1 && s[start] === '.'))
      throw new Error('Invalid expression');
    return parseFloat(s.slice(start, i));
  }

  const result = parseExpr();
  skipSpaces();
  if (i !== s.length) throw new Error('Invalid expression');
  return result;
}
```

    563 tokens in, 595 out (118 of them reasoning) · 11.1 s · $0.0004 · 1 message on Pro · answered by z-ai/glm-5.3-flash via AtlasCloud ·

  5. Parse CSV with quoted fields

    A hard prompt: “Parse CSV with quoted fields”, in full.

    Passed: All 8 tests passed.

    ```javascript
function parseCsv(text) {
  if (text === "") return [];
  const rows = [];
  let row = [];
  let field = "";
  let inQuotes = false;
  let i = 0;
  // Track whether the field started with a quote
  let fieldQuoted = false;

  function endField() {
    row.push(field);
    field = "";
    fieldQuoted = false;
  }

  function endRow() {
    endField();
    rows.push(row);
    row = [];
  }

  while (i < text.length) {
    const ch = text[i];

    if (inQuotes) {
      if (ch === '"') {
        if (text[i + 1] === '"') {
          field += '"';
          i += 2;
        } else {
          inQuotes = false;
          i++;
        }
      } else {
        field += ch;
        i++;
      }
      continue;
    }

    if (field === "" && !fieldQuoted && ch === '"') {
      fieldQuoted = true;
      inQuotes = true;
      i++;
      continue;
    }

    if (ch === ",") {
      endField();
      i++;
      continue;
    }

    if (ch === "\r" || ch === "\n") {
      // handle \r\n as one line break
      if (ch === "\r" && text[i + 1] === "\n") i++;
      // a line break at the very end of the text doesn't start a new row
      if (i + 1 >= text.length || (ch === "\r" && i + 2 >= text.length)) {
        i++;
        continue;
      }
      endRow();
      i++;
      continue;
    }

    field += ch;
    i++;
  }

  // final field/row if anything pending (a field was started)
  if (field !== "" || fieldQuoted || row.length > 0) {
    endRow();
  }

  return rows;
}
```

    495 tokens in, 434 out (8 of them reasoning) · 8.4 s · $0.0003 · 1 message on Pro · answered by z-ai/glm-5.3-flash via AtlasCloud ·

How it compares on coding

GLM 5.3 Flash beside the job's picks among every model. 13 models share the hard-problems pick, GLM 5.3 Flash among them.

GLM 5.3 Flash beside other models on coding
ModelPassedOn ProCost per reply
GLM 5.3Our pick: hard problems (shared), best value5 of 5250 a month on Pro$0.0015
GLM 5.3 FlashOur pick: hard problems (shared), everyday5 of 560 a day on Pro$0.0003
On Pro: Pro's count on each model. Cost: what OpenRouter charged us per reply, on average.

Every limit is published. Paid plans also have a monthly fair-use limit on AI cost: Pro $7.50, Max $20, Ultra $42, Studio $85. Using every message on your plan at typical sizes stays under it; very large messages and heavy research use it faster. Every limit, explained.

How these runs were done

Tests. Automatic. The function runs against the prompt's tests in a separate Node.js process with a time limit and no file, network or child-process access; it passes when every test passes.

How the runs were done, and every coding prompt.

GLM 5.3 Flash, and coding, elsewhere

Questions

Is GLM 5.3 Flash good for coding?

In our test runs it passed 5 of 5 coding prompts, tied 1st of the 15 models in llmwise. Every reply is on this page, so you can judge them yourself.

How many of my messages does a coding reply from GLM 5.3 Flash use?

1 message each on Pro, where it has 60 a day on Pro. The price of a message is fixed and shown before you send it, however long the reply.

How were these runs done?

The same way for every model: each prompt sent through llmwise's own pipeline, each reply checked the same way. The methods page has every prompt and how each is scored.

Claude, GPT, Gemini, DeepSeek, Grok, Kimi, and GLM, in one chat.

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