How do I decode a Base64 string online?

Paste your Base64 string into SmartDevBox at smartdevbox.com. It automatically detects Base64 encoding and decodes it instantly — no configuration needed.

How do I decode a JWT token without a secret?

Paste your JWT token into SmartDevBox. The JWT Inspector tool decodes the header and payload and displays them as readable JSON. Note: this decodes but does not verify the signature — you don't need the secret to read the claims.

How do I format or pretty-print JSON?

Paste your minified or unformatted JSON into SmartDevBox. The JSON Formatter tool detects it automatically and pretty-prints it with configurable indentation.

How do I convert a Unix timestamp to a human-readable date?

Paste a Unix timestamp (e.g. 1700000000) into SmartDevBox. The Unix Timestamp converter detects it and shows the equivalent date and time in UTC and your local timezone.

How do I convert JSON to CSV?

Paste a JSON array of objects into SmartDevBox and select the JSON → CSV tool. It converts your data to comma-separated format with headers derived from the JSON keys.

How do I compute a SHA-256 hash online?

Use the Hash Generator tool on SmartDevBox. Paste any text and it computes MD5, SHA-1, SHA-256, and SHA-512 hashes simultaneously in the browser.

How do I parse and understand a cron expression?

Paste your cron expression (e.g. "0 9 * * 1-5") into SmartDevBox. The Cron Job Parser explains it in plain English and shows the next scheduled run times.

How do I decode an X.509 certificate online?

Paste a PEM-encoded certificate (beginning with -----BEGIN CERTIFICATE-----) into SmartDevBox. The Certificate Decoder extracts and displays the subject, issuer, validity dates, public key, and extensions.

Is SmartDevBox free to use?

Yes. SmartDevBox is completely free with no account or sign-up required. All tools run in the browser. An optional AI mode (for ambiguous input detection) can be enabled with your own OpenAI API key.

Does SmartDevBox send my data to a server?

No. All tools run entirely in the browser using client-side JavaScript. Your data never leaves your machine unless you opt into the AI mode, which sends input to OpenAI for format detection.

UUID Generator — Generate UUID v4 Online, Free

UUID Generator creates cryptographically random UUID version 4 identifiers using the browser's crypto.randomUUID() API. You can generate a single UUID or up to 1000 at once.

Common Use Cases

Generating unique identifiers for database records
Creating correlation IDs for distributed system tracing
Generating UUIDs for test data fixtures
Creating unique IDs for feature flags or A/B test variants

Frequently Asked Questions

What is a UUID v4?

A UUID (Universally Unique Identifier) version 4 is a 128-bit number generated using random or pseudo-random numbers, formatted as xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The v4 variant has extremely low collision probability.

How is a UUID different from a ULID?

UUIDs are random and do not sort chronologically. ULIDs (Universally Unique Lexicographically Sortable Identifiers) embed a millisecond timestamp prefix, so they sort by creation time and are database-index-friendly.

Privacy & Security

This tool runs entirely in your browser using client-side JavaScript. No data is sent to a server — your input never leaves your machine. SmartDevBox has no account system, no usage tracking, and no paid tier. See the Privacy & Security page for full details.

ULID GeneratorGenerate Universally Unique Lexicographically Sortable Identifiers (ULIDs). Free, no sign-up, 100% client-side.
Random String GeneratorGenerate random strings with configurable length and character set. Free, no sign-up, 100% client-side.
Hash GeneratorCompute MD5, SHA-1, SHA-256, and SHA-512 hashes for any text. Free, no sign-up, 100% client-side.
UUID to Hex ConverterConvert between standard UUID format and 32-character hex strings instantly. Free, no sign-up, 100% client-side.