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Claude Opus 5.5 · Coding

Claude Opus 5.5 for coding: our test runs

Claude Opus 5.5 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, Claude Opus 5.5 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 62 a month, and cost $0.0171 to run on average.

Prompt by prompt

Each of the 5 coding prompts, and how Claude Opus 5.5's reply did.

Claude Opus 5.5 on each coding prompt
PromptResultCostTime
Turn a title into a URL slugEverydayPassed: All 7 tests passed.$0.00553.1 s
Parse a duration like “1h 30m”EverydayPassed: All 10 tests passed.$0.01127.2 s
Merge overlapping intervalsEverydayPassed: All 7 tests passed.$0.00773.7 s
Evaluate an arithmetic expression, no evalHardPassed: All 15 tests passed.$0.033615.8 s
Parse CSV with quoted fieldsHardPassed: All 8 tests passed.$0.027311.9 s

Every coding reply from Claude Opus 5.5

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

    671 tokens in, 112 out · 3.1 s · $0.0055 · 1 message on Pro · answered by anthropic/claude-opus-5.5 via Claude Platform on AWS ·

  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 match = /^\s*(?:(\d+)h)?\s*(?:(\d+)m)?\s*(?:(\d+)s)?\s*$/.exec(text);
  if (!match) return null;

  const [, h, m, s] = match;
  if (h === undefined && m === undefined && s === undefined) return null;

  return (
    (h !== undefined ? Number(h) * 3600 : 0) +
    (m !== undefined ? Number(m) * 60 : 0) +
    (s !== undefined ? Number(s) : 0)
  );
}
```

    626 tokens in, 406 out (182 of them reasoning) · 7.2 s · $0.0112 · 1 message on Pro · answered by anthropic/claude-opus-5.5 via Claude Platform on AWS ·

  3. Merge overlapping intervals

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

    Passed: All 7 tests passed.

    ```javascript
function mergeIntervals(intervals) {
  if (!Array.isArray(intervals) || intervals.length === 0) return [];

  const sorted = intervals
    .map(([start, end]) => [start, end])
    .sort((a, b) => a[0] - b[0] || a[1] - b[1]);

  const result = [sorted[0]];

  for (let i = 1; i < sorted.length; i++) {
    const last = result[result.length - 1];
    const [start, end] = sorted[i];

    if (start <= last[1]) {
      if (end > last[1]) last[1] = end;
    } else {
      result.push([start, end]);
    }
  }

  return result;
}
```

    621 tokens in, 234 out · 3.7 s · $0.0077 · 1 message on Pro · answered by anthropic/claude-opus-5.5 via Claude Platform on AWS ·

  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) {
  if (typeof expression !== "string") {
    throw new Error("Expression must be a string");
  }

  // Tokenizer
  const tokens = [];
  const numberRe = /\d+(?:\.\d+)?|\.\d+/y;
  let i = 0;
  while (i < expression.length) {
    const ch = expression[i];
    if (/\s/.test(ch)) {
      i++;
      continue;
    }
    if ("+-*/^()".includes(ch)) {
      tokens.push({ type: ch });
      i++;
      continue;
    }
    numberRe.lastIndex = i;
    const m = numberRe.exec(expression);
    if (m) {
      tokens.push({ type: "num", value: parseFloat(m[0]) });
      i += m[0].length;
      continue;
    }
    throw new Error(`Unexpected character '${ch}' at position ${i}`);
  }

  // Recursive descent parser
  let pos = 0;
  const peek = () => tokens[pos];
  const accept = (type) => {
    if (tokens[pos] && tokens[pos].type === type) {
      pos++;
      return true;
    }
    return false;
  };

  // expr := term (('+' | '-') term)*
  function parseExpr() {
    let value = parseTerm();
    for (;;) {
      if (accept("+")) value += parseTerm();
      else if (accept("-")) value -= parseTerm();
      else return value;
    }
  }

  // term := unary (('*' | '/') unary)*
  function parseTerm() {
    let value = parseUnary();
    for (;;) {
      if (accept("*")) value *= parseUnary();
      else if (accept("/")) value /= parseUnary();
      else return value;
    }
  }

  // unary := '-' unary | power
  function parseUnary() {
    if (accept("-")) return -parseUnary();
    return parsePower();
  }

  // power := primary ('^' unary)?   (right-associative; exponent may be negated)
  function parsePower() {
    const base = parsePrimary();
    if (accept("^")) {
      const exponent = parseUnary();
      return Math.pow(base, exponent);
    }
    return base;
  }

  // primary := number | '(' expr ')'
  function parsePrimary() {
    const tok = peek();
    if (!tok) throw new Error("Unexpected end of expression");
    if (tok.type === "num") {
      pos++;
      return tok.value;
    }
    if (accept("(")) {
      const value = parseExpr();
      if (!accept(")")) throw new Error("Expected ')'");
      return value;
    }
    throw new Error(`Unexpected token '${tok.type}'`);
  }

  if (tokens.length === 0) throw new Error("Empty expression");
  const result = parseExpr();
  if (pos !== tokens.length) {
    const tok = tokens[pos];
    throw new Error(
      `Unexpected token '${tok.type === "num" ? tok.value : tok.type}'`
    );
  }
  return result;
}
```

    762 tokens in, 1,491 out (435 of them reasoning) · 15.8 s · $0.0336 · 1 message on Pro · answered by anthropic/claude-opus-5.5 via Claude Platform on AWS ·

  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) {
  const rows = [];
  const n = text.length;
  if (n === 0) return rows;

  let row = [];
  let field = '';
  let inQuotes = false;
  let atFieldStart = true; // no characters consumed yet for the current field
  let rowPending = false;  // current row has consumed at least one character
  let i = 0;

  while (i < n) {
    const c = text[i];

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

    if (c === '"' && atFieldStart) {
      inQuotes = true;
      atFieldStart = false;
      rowPending = true;
      i += 1;
      continue;
    }

    if (c === ',') {
      row.push(field);
      field = '';
      atFieldStart = true;
      rowPending = true;
      i += 1;
      continue;
    }

    if (c === '\n' || (c === '\r' && text[i + 1] === '\n')) {
      row.push(field);
      rows.push(row);
      row = [];
      field = '';
      atFieldStart = true;
      rowPending = false;
      i += c === '\r' ? 2 : 1;
      continue;
    }

    field += c;
    atFieldStart = false;
    rowPending = true;
    i += 1;
  }

  if (rowPending || inQuotes) {
    row.push(field);
    rows.push(row);
  }

  return rows;
}
```

    669 tokens in, 1,200 out (637 of them reasoning) · 11.9 s · $0.0273 · 1 message on Pro · answered by anthropic/claude-opus-5.5 via Claude Platform on AWS ·

How it compares on coding

Claude Opus 5.5 beside the job's picks among every model. 13 models share the hard-problems pick, Claude Opus 5.5 among them.

Claude Opus 5.5 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
Claude Opus 5.5Our pick: hard problems (shared)5 of 562 a month on Pro$0.0171
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.

Claude Opus 5.5, and coding, elsewhere

Questions

Is Claude Opus 5.5 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 Claude Opus 5.5 use?

1 message each on Pro, where it has 62 a month 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.

See what a message costs before you send it. Free is 5 messages to try; sign in with an email link, no password or card.

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