Random String Generator

How to Use the Random String Generator

Enter exactly the characters you want to use, or build the editable set with the quick-setting buttons. Choose a length from 1 to 256, set a quantity from 1 to 100, and optionally exclude characters that are easy to confuse. Generate creates each string with a separate crypto.getRandomValues() call. Copy one result, copy the newline-separated batch, or download a text file.

Why Custom Character Sets and Bulk Output Matter

Random strings are not limited to account passwords. A hex-only set can match an existing token format; an unambiguous uppercase set suits printed coupon codes; and a URL-safe set avoids escaping in routes. Bulk generation helps seed fixture data, prepare one-time IDs, and test import pipelines.

For account credentials, continue to use the Password Generator, which provides password-specific choices and strength feedback. This tool focuses on custom formats and multiple non-password outputs.

ランダム文字列ジェネレーターの使い方

文字セット欄へ使用したい文字を直接入力するか、クイック設定で大文字・小文字・数字・記号・Hexを追加または削除します。長さ(1〜256)と個数(1〜100)を指定して生成してください。結果は個別コピー、改行区切りの全件コピー、または.txtで保存できます。紛らわしい文字の除外は生成時だけ適用され、入力欄の内容は失われません。

カスタム文字セット・一括生成が有用な場面

• テスト用APIキー -- 本番形式に合わせたダミー値をまとめて用意
• クーポンコード -- ABCDEFGHJKLMNPQRSTUVWXYZ23456789で誤読しにくいコードを生成
• 一時ID・フィクスチャ -- URLやデータベースの制約に合わせて一括生成

よくある落とし穴と対処 / Common Pitfalls

言語別コード例 / Code Examples

JavaScript (Web Crypto)

const charset = "0123456789abcdef";
const values = new Uint32Array(24);
crypto.getRandomValues(values);
const token = Array.from(values, (v) => charset[v % charset.length]).join("");

Python (secrets)

import secrets
charset = "ABCDEFGHJKLMNPQRSTUVWXYZ23456789"
codes = ["".join(secrets.choice(charset) for _ in range(12)) for _ in range(10)]

Node.js (crypto.randomBytes)

const { randomBytes } = require("node:crypto");
const charset = "0123456789abcdef";
const token = Array.from(randomBytes(24), (v) => charset[v % charset.length]).join("");

Shell (openssl rand)

openssl rand -hex 16
openssl rand -base64 24

生成例 / Before & After

Before: charset=0123456789abcdef, length=16, quantity=3
After:
9f31a5c082e4d7b6
06bd79e12a83fc45
c48e0271bd96a53f

Before: charset=ABCDEFGHJKLMNPQRSTUVWXYZ23456789, length=10, quantity=3
After:
X7M2KQ9W4Z
BH6T3NP8RY
Q4V9G2K7MC

Why browser-only?

Tokens and IDs may grant access, identify private records, or become fixtures copied into sensitive systems. A server-side generator could expose them to network paths, memory, or logs. This tool generates, displays, copies, and exports every string inside your browser. Nothing is transmitted or stored. Watch the DevTools Network tab while generating: the operation creates zero requests.

トークンやIDはアクセス権限や非公開データに結びつく場合があります。本ツールは生成・表示・コピー・ファイル作成の全てがブラウザ内で完結し、生成結果を外部へ送信・保存しません。

Frequently Asked Questions / よくある質問