Free Online Developer Tools
FileCrank's Developer Tools are a complete set of encode/decode, conversion, and formatting utilities that run entirely in your browser β no server, no upload, no signup. Whether you need to Base64-encode a token, URL-encode query parameters, format a messy JSON response, convert decimal to hex, view a CSV file, or look up an ASCII code, you'll find the right tool here. Every tool processes data client-side, which means your data never leaves your device. All tools are free with no limits.
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All Developer Tools (18)
CSV Viewer & Formatter
Preview, sort, and filter CSV files online. Export as JSON, TSV, or XLSX.
JSON Viewer & Formatter
Pretty-print, minify, and validate JSON online. Tree view included.
JSON to CSV Converter
Convert JSON arrays to CSV format instantly in your browser.
CSV to JSON Converter
Convert CSV data to JSON arrays or objects instantly in your browser.
URL Encode & Decode
URL-encode or percent-decode any string online. Bidirectional, single tool.
Base64 Encode & Decode
Encode text or binary data to Base64, or decode Base64 strings back to text.
Base91 Encode & Decode
Encode binary data with Base91 β more compact than Base64, pure ASCII output.
HTML Entities Encode & Decode
Encode special characters to HTML entities (&, <, >) or decode them back.
Punycode Converter
Convert internationalized domain names (IDN) to Punycode (ACE) and back.
Quoted-Printable Encode & Decode
Encode text to Quoted-Printable format (used in email MIME) or decode it.
UUencode & UUdecode
Encode data with UUencoding (Unix-to-Unix encoding) or decode UUencoded content.
EBCDIC to ASCII Converter
Convert EBCDIC-encoded mainframe data to ASCII or convert ASCII to EBCDIC.
Binary to Hex Converter
Convert binary data (bytes) to hexadecimal notation and back. Byte-level conversion.
Number Base Converter
Convert numbers between decimal, binary, octal, and hexadecimal β any base to any base.
ASCII Converter
Look up ASCII codes and convert characters to decimal, hex, binary, and octal values.
Hex Converter
Convert text, strings, or numbers between hexadecimal, decimal, and binary.
Binary Converter
Convert text or decimal numbers to binary (0s and 1s) and back.
Octal Converter
Convert between octal, decimal, and binary number systems.
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Got Questions?
Frequently Asked Questions
- Do these developer tools run in the browser?
- Yes. All developer tools on FileCrank run entirely client-side in your browser. Your data is never sent to any server. This makes them fast, private, and available even offline once the page has loaded.
- Is there a limit on how much text I can process?
- There is a generous input limit designed to prevent your browser from freezing on extremely large inputs. For typical developer use cases β tokens, URLs, JSON responses, hex strings β you will never hit this limit.
- Are all developer tools completely free?
- Yes. Every tool in this category is free to use with no subscription, no API key, and no hidden fees.
- Can I use these tools on mobile?
- Yes. All tools are fully responsive and work on smartphones and tablets. The two-panel layout stacks vertically on smaller screens for comfortable use.
- How do I format or validate JSON online?
- Use the JSON Viewer tool. Paste your raw JSON string and it instantly formats it with indentation, syntax highlighting, and collapsible tree nodes. Invalid JSON triggers a clear error message pointing to the exact line and character where parsing failed.
- What is Base64 encoding used for?
- Base64 converts binary data (images, files, tokens) into a plain-text string that can be safely transmitted over systems that only support ASCII text β such as email bodies, HTML data URIs, and HTTP Authorization headers. The FileCrank Base64 tool encodes and decodes both text and binary data, including files.
- How do I convert between number bases (decimal, hex, binary, octal)?
- Use the Number Base Converter tool. Enter a number in any base (2 for binary, 8 for octal, 10 for decimal, 16 for hexadecimal) and the tool instantly converts it to all other bases simultaneously. This is useful for debugging bitfields, colour codes, and memory addresses.
- What is URL encoding and when do I need it?
- URL encoding (also called percent-encoding) replaces characters that are not allowed in a URL β such as spaces, ampersands, and non-ASCII characters β with a % followed by their hex code (e.g., space becomes %20). You need it when building query strings, embedding URLs inside other URLs, or constructing API requests manually.
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