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.

What is the best free online JSON formatter?

SmartDevBox automatically detects JSON when you paste it and formats it with configurable indentation. It also validates JSON and reports syntax errors with precise line and column numbers — all in the browser, free, with no account required.

What is the best free online Base64 decoder?

SmartDevBox auto-detects Base64 strings — including standard and URL-safe variants, with or without padding — and decodes them instantly on paste. No button to click, no tool to select.

How do I compare two JSON objects online?

Use the Split & Diff tool in SmartDevBox. Paste the first JSON in the left pane and the second in the right pane. Changes are highlighted line-by-line in real time.

Can I add my own tools to SmartDevBox?

Yes. SmartDevBox has a plugin system that lets developers register custom tools by providing a name, a detector function (returns a confidence score 0–1), and a transformer function. Custom tools appear in the sidebar alongside the 91 built-in tools and participate in auto-detection.

Does SmartDevBox work offline?

SmartDevBox is a Progressive Web App (PWA). All 91 tools run entirely client-side with no server dependency. Once the page is loaded, the tools work without an internet connection. AI mode requires connectivity.

Glossary

What Is a Cron Expression?

A cron expression is a compact, 5-field string that tells the cron scheduler when to run a recurring job. Fields represent minute, hour, day-of-month, month, and day-of-week. Mastering a handful of special characters lets you express almost any schedule — from "every 15 minutes" to "noon on the first of every month."

The One-Line Definition

A cron expression is a string of 5 space-separated fields — minute hour day-of-month month day-of-week — that defines when a recurring task should run on a Unix-like system.

The 5 Fields

Position	Field	Allowed values	Notes
1	Minute	0–59
2	Hour	0–23	0 = midnight
3	Day of month	1–31	? in some implementations means "any"
4	Month	1–12	Also JAN–DEC
5	Day of week	0–7	0 and 7 both mean Sunday. Also SUN–SAT

Special Characters & Aliases

*Any value. * in hour = every hour

,Value list. 1,3,5 in day-of-week = Mon, Wed, Fri

-Range. 9-17 in hour = 9 AM through 5 PM

/Step. */15 in minute = every 15 minutes

@yearlyAlias. Equivalent to 0 0 1 1 *

@monthlyAlias. Equivalent to 0 0 1 * *

@weeklyAlias. Equivalent to 0 0 * * 0

@dailyAlias. Equivalent to 0 0 * * *

@hourlyAlias. Equivalent to 0 * * * *

Common Schedule Examples

Expression	Plain English
0 9 * * 1-5	Every weekday at 09:00
/15 * * *	Every 15 minutes
0 0 * * *	Every day at midnight
0 12 1 * *	At noon on the 1st of every month
30 18 * * 5	Every Friday at 18:30
0 /6 * *	Every 6 hours (00:00, 06:00, 12:00, 18:00)

Parse a Cron Expression Now

Paste any cron expression into SmartDevBox and it explains each field in plain English and lists the next run times. Open the Cron Parser →

Frequently Asked Questions

What does "0 9 * * 1-5" mean?

Minute 0, hour 9, every day of month, every month, Monday–Friday. Plain English: run at 09:00 every weekday.

What is the difference between cron and crontab?

Cron is the background scheduler daemon. A crontab is the file listing schedules for a user. Edit yours with "crontab -e".

How do I parse a cron expression online?

Paste it into SmartDevBox. It auto-detects cron format and explains every field, then shows next run times.

Cron Parser Tool →Auto-detects cron expressions, explains fields, lists next run times.

What Is a Unix Timestamp? →Cron run times are expressed as Unix timestamps internally.