> For AI agents: the complete documentation index is available at /en/llms.txt, the full documentation bundle is available at /en/llms-full.txt.

# Brace Expander

[Brace Expander](https://tools.newzone.top/en/brace-expander) is for the case where one rule has to yield nine names or a hundred: a database migration that needs 100 field names, a batch of URLs, renamed files, or the contents of a SQL `IN (...)`. **Write the rule once; it lists every combination.**

The syntax is bash brace expansion, so the output matches bash line for line — whatever you can verify in a shell, you get the same here.

![Brace Expander interface](/img/brace-expander-en.webp "Brace Expander interface")

:::tip 30-second quickstart

1. Write one line in the **template** box, e.g. `f{1..4}pd_ever_od30_{tag,bal}`
2. All eight names appear live below — **click the example in the empty state to fill it in**
3. Copy or export. To wrap into SQL or JSON, open **Advanced settings**

:::

## Template syntax

One template per line; several lines concatenate in order and each expands on its own. Braces inside a line expand:

| Form           | Meaning                                                      |
| -------------- | ------------------------------------------------------------ |
| `{1..100}`     | integer range, 1 through 100                                 |
| `{1..100..2}`  | with a step: 1, 3, 5 …                                       |
| `{001..100}`   | zero-padded to three digits                                  |
| `{a..e}`       | letter range, same rules as integers, steps too: `{a..c..2}` |
| `{tag,bal}`    | list                                                         |
| `\{` `\}` `\,` | literals, backslash consumed: `a\{b,c\}d` → `a{b,c}d`        |

Zero-padding takes its width **from the literal width of the start value**; the end never shrinks it: `{001..10}` gives `001 … 010`. Whether you want `f001` or `f1` is yours to write in the template.

## Several groups combine on their own

Multiple brace groups form a Cartesian product without you writing one:

```
f{1..2}_{tag,bal}   →   f1_tag  f1_bal  f2_tag  f2_bal
```

## Output order

**Advanced settings** holds an output-order switch deciding **which brace group runs slowest**:

- **Interleave** (default, matches bash): `{a,b}{1,2}` → `a1 a2 b1 b2`, with the **leftmost brace outer**. `f{1..4}_tag,bal` gives f1…\_tag, f1…\_bal, f2…\_tag …
- **Grouped**: same template → `a1 b1 a2 b2`, with the **rightmost brace outer**, running all the way through before the left one advances. Use it when you need all the tags before all the bals

Both modes produce **exactly the same items**; only the arrangement changes.

Several template lines always concatenate in line order — the switch only applies to groups within a single line.

## Assembly

The shape is **prefix · line ⟨separator⟩ line · suffix**:

- **Line separator**: newline `\n` by default; `, ` for SQL `IN`
- **Global prefix / suffix**: the start and end of the whole result, e.g. `[\n` and `\n]` for a JSON array

Common recipes:

- **Field names** — template `f{1..100}pd_ever_od30_{tag,bal}`
- **URL list** — `https://example.com/{a,b,c}/{1..20}`
- **Filenames** — `img_{001..100}.png`
- **SQL `IN (...)`** — template `'{1}'`, separator `, `, prefix `IN (`, suffix `)`
- **SQL `INSERT`** — template `('{1}', '{2}')`, separator `,\n`, prefix `INSERT INTO t (a, b) VALUES\n`, suffix `;`
- **JSON array** — template `"{1}"`, separator `,\n`, prefix `[\n`, suffix `\n]`

## Template history

Keep the few recipes you reuse in the history and pull them back in one click. The row stays off the first screen while the history is empty — it returns on its own after the first save.

## Limits

- **The ceiling is 10,000 lines per run**, a deliberate departure from bash, which has no limit. Past it, **no partial result is produced**; the reason is shown so you can narrow the range instead of shipping half a list
- **Grouped order is not bash behaviour** — see above
- **Typos stay literal.** `{a}`, `{1..}` and `{1..3.5}` are not valid brace forms, so they come out exactly as written rather than raising an error, which makes a broken template obvious instead of silently short