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.

SQL (Structured Query Language) is the standard language for interacting with relational databases. It lets you create schema objects (DDL), read and write data (DML), and control access (DCL). SQL is declarative — you describe what data you want, and the database engine decides how to retrieve it.

Glossary

What Is SQL?

SQL (Structured Query Language) is the standard language for interacting with relational databases. Pronounced "sequel" or "S-Q-L", it is declarative — you describe what data you want, and the engine decides how to find it. Nearly every application that stores structured data uses SQL under the hood.

The One-Line Definition

SQL is a domain-specific language standardised by ANSI/ISO for defining, querying, and controlling data in relational database management systems (RDBMS) such as PostgreSQL, MySQL, SQLite, SQL Server, and Oracle.

A Basic Query

SELECT
  u.id,
  u.name,
  COUNT(o.id) AS order_count
FROM users u
LEFT JOIN orders o ON o.user_id = u.id
WHERE u.created_at >= '2024-01-01'
GROUP BY u.id, u.name
HAVING COUNT(o.id) > 0
ORDER BY order_count DESC
LIMIT 10;

DDL, DML, DCL, TCL

DDL — Data Definition LanguageCREATE TABLE, ALTER TABLE, DROP TABLE, CREATE INDEX
Define and modify schema structure.

DML — Data Manipulation LanguageSELECT, INSERT, UPDATE, DELETE, MERGE
Read and write rows.

DCL — Data Control LanguageGRANT, REVOKE
Manage user permissions and access.

TCL — Transaction Control LanguageBEGIN, COMMIT, ROLLBACK, SAVEPOINT
Control multi-statement transactions.

Query Anatomy

SELECTChoose which columns to return. Use * for all columns or list specific ones.

FROMSpecify the base table (or subquery) to read from.

JOIN … ONCombine rows from a second table using a key relationship.

WHEREFilter rows before grouping. Cannot reference aggregate functions.

GROUP BYCollapse multiple rows into groups for aggregation (COUNT, SUM, AVG…).

HAVINGFilter groups after aggregation. Can reference aggregate functions.

ORDER BYSort the result set. ASC (default) or DESC.

LIMIT / TOPReturn only the first N rows. Syntax varies by database.

JOIN Types

INNER JOINOnly rows with a match in both tables.

LEFT JOINAll rows from the left table; NULLs for unmatched right rows.

RIGHT JOINAll rows from the right table; NULLs for unmatched left rows.

FULL OUTER JOINAll rows from both tables; NULLs where no match.

CROSS JOINCartesian product — every left row paired with every right row.

SELF JOINA table joined to itself, typically to find hierarchical relationships.

Format SQL Now

SQL Formatter → — indent clauses, uppercase keywords, align columns. All client-side.

Frequently Asked Questions

What is the difference between DDL, DML, and DCL?

DDL (CREATE, ALTER, DROP) defines schema. DML (SELECT, INSERT, UPDATE, DELETE) works with data. DCL (GRANT, REVOKE) manages permissions. TCL (COMMIT, ROLLBACK) controls transactions.

How do SQL JOINs work?

A JOIN combines rows from two tables based on a related column. INNER JOIN returns only matches. LEFT JOIN returns all left rows plus matched right rows (NULLs where no match).

What is the difference between WHERE and HAVING?

WHERE filters individual rows before grouping. HAVING filters groups after aggregation and can reference aggregate functions like COUNT() or SUM().

How do I format SQL online?

Paste your query into SmartDevBox SQL Formatter. It indents clauses and uppercases keywords instantly, all in the browser.

SQL Formatter →Format and indent SQL queries in the browser.

What Is JSON? →JSON is the common data interchange format used in REST APIs alongside SQL databases.

What Is CSV? →CSV is a common export format for SQL query results.