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psb
Photoshop Big
The PSB file format, also known as "Photoshop Big," is an Adobe Photoshop file format des…
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Instantly look up any file extension to discover what it is, which software opens it, which operating systems support it, and what alternative formats exist. From everyday .pdf and .jpg to rare scientific and engineering formats — every answer is one search away.
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A file extension is the short group of letters after the final dot in a filename. When you see invoice.pdf the extension is .pdf. When you see photo.jpeg the extension is .jpeg. These suffixes look minor but carry critical information your computer depends on every single day.
Your operating system reads the extension the moment you double-click a file and uses it to decide which application should open it. Without extensions, Windows, macOS, and Linux would have no reliable way to distinguish a spreadsheet from a song, or a video from a log file.
File extensions also communicate the encoding format of the data inside. A .png image is compressed differently from a .bmp image even though both contain pixel data. A .mp3 audio file uses lossy compression while .flac is lossless — the extension tells you which trade-off was made when the file was saved.
Understanding extensions helps you troubleshoot compatibility problems, choose the right format before saving, and avoid accidentally corrupting a file by renaming it with the wrong suffix. This directory gives you accurate, sourced information about every extension so you can make informed decisions.
Browse All ExtensionsEvery file type belongs to a category. Select one below to explore all extensions in that group, complete with descriptions, compatible software, and conversion options.
Not all file extensions are equal. Some you encounter every day; others appear only in specialised workflows. Here is a plain-English overview of the categories you are most likely to encounter.
Document extensions store text, formatting, and embedded media. .docx (Microsoft Word) and .odt (OpenDocument) are editable word-processor files. .pdf locks the layout so it looks identical on every device — ideal for contracts and invoices. .txt contains plain text with no formatting at all, making it universally readable. .rtf sits between the two, preserving basic styling without locking to a specific application.
Image extensions define how pixel data is stored and compressed. .jpg uses lossy compression — perfect for photographs where small file size matters more than perfection. .png is lossless and supports transparency, making it the go-to for logos and screenshots. .webp is a modern format offering superior compression for both photos and graphics. .heic is Apple's default for iPhones; .raw captures every detail straight from the camera sensor without any processing.
Audio extensions split into two camps: lossy and lossless. .mp3 is the world's most recognised audio format — it discards frequencies the human ear barely notices to achieve small file sizes. .aac does the same job with better quality at the same bitrate. .flac and .wav preserve every bit of the original recording, the choice of audiophiles and audio engineers. .ogg is an open-source lossy format with no licensing fees, popular in games and streaming.
Video extensions are often containers — they wrap together a video stream, an audio stream, and sometimes subtitles. .mp4 (MPEG-4 Part 14) is the dominant container on the web and mobile devices. .mkv (Matroska) is preferred by enthusiasts for its flexibility and support for multiple audio tracks. .mov is Apple's container, widely used in Final Cut Pro. .avi is an older Microsoft format still common in legacy archives. .webm is the open-source web-native option.
Archive formats bundle multiple files into one and usually compress them. .zip is the universal standard — built into Windows, macOS, and Linux with no extra software needed. .rar often achieves better compression ratios but requires third-party software to create. .7z (7-Zip) leads in compression efficiency for very large files. .tar.gz and .tar.bz2 are staples in the Linux and macOS worlds, bundling files into a tarball then compressing with gzip or bzip2.
Code and data extensions are the backbone of software development. .py contains Python source code; .js holds JavaScript; .cpp stores C++ source. Data exchange formats like .json and .xml transmit structured data between applications and APIs. .csv stores tabular data in plain text that every spreadsheet can read. .sql contains database queries and schema definitions. .yaml and .toml are popular for configuration files in modern DevOps workflows.
The file types people search for most often. Click any card to see compatible software, OS support, and format alternatives.
The PSB file format, also known as "Photoshop Big," is an Adobe Photoshop file format des…
BildA VBS file is a text file containing code written in Visual Basic Scripting Edition (VBSc…
ProgrammierungThe .ts file extension represents a Transport Stream file, a video stream format primaril…
VideoThe ODT file extension represents a text document format used by word processors. It is t…
DokumentASP.NET files, typically using the `.aspx` extension (the extension value we'll focus on)…
ProgrammierungThe Ogg file format is a free, open container format maintained by the Xiph.Org Foundatio…
AudioMP3 (MPEG Audio Layer III) is a widely used audio coding format for digital audio. It's k…
AudioXSL (Extensible Stylesheet Language) is a family of languages used for transforming and f…
DatenThe 7z file extension represents an archive format used by the 7-Zip file archiver. It is…
ArchivA 'js' file is a plain text file containing JavaScript code. JavaScript is a high-level, …
ProgrammierungThe .img file extension is primarily associated with ERDAS Imagine, a powerful geospatial…
BildA .ps1 file is a text file containing commands written in the PowerShell scripting langua…
ProgrammierungA .BTM file is a batch file used by Take Command Console (TCC), a command-line interprete…
AusführbarA PHTML file is a web page file containing PHP code. It's essentially an HTML file with e…
ProgrammierungA .BAT file is a batch file containing a series of commands to be executed by the command…
AusführbarA .tsx file is a TypeScript file that includes JSX syntax. TypeScript is a superset of Ja…
ProgrammierungJSP (JavaServer Pages) is a technology that allows developers to create dynamic web pages…
ProgrammierungFLAC (Free Lossless Audio Codec) is an audio coding format for lossless compression of di…
AudioThe `.cjs` file extension is used for JavaScript files that contain code written using th…
ProgrammierungreStructuredText (RST, ReST, or reST) is a plain text markup syntax similar to Markdown. …
DatenThe Motorola S-Record file format, often shortened to SREC or S19, is a text-based file f…
ProgrammierungAn OLE Control Extension (OCX) file is a type of dynamic-link library (DLL) used in Micro…
AusführbarPHP files contain code written in the PHP scripting language. PHP is a widely-used open s…
ProgrammierungAdvanced Audio Coding (AAC) is a standardized, lossy audio compression and encoding schem…
AudioThe Apache Arrow IPC Stream format (.arrow) is a binary file format designed for efficien…
DatenThe Wavefront .OBJ file format is a geometry definition file format first developed by Wa…
DatenGeoTIFF is a public domain metadata standard which allows georeferencing information to b…
DatenA CSHTML file is a web page that uses Razor syntax with C# code. It's primarily used in A…
ProgrammierungAn IPSW file is a proprietary archive format used by Apple to distribute firmware updates…
ArchivA ZIP file is a compressed archive format that can contain one or more files and folders.…
ArchivA '.py' file is a source code file written in the Python programming language. Python is …
ProgrammierungActiveX controls are small programs, also known as add-ons, that are used on the Internet…
AusführbarThe .mot file extension represents a Motorola S-Record file. This is a text-based file fo…
DatenJPEG (Joint Photographic Experts Group) is a widely used method of lossy compression for …
BildOpus is a lossy audio coding format developed by the Internet Engineering Task Force (IET…
AudioThe MKV file format is a flexible, open standard video file format, a container format th…
VideoAn EXE file is a common file extension for executable files in Windows operating systems.…
AusführbarThe DOCX file extension represents a Microsoft Word Open XML Document. Introduced with Mi…
DokumentRich Text Format (RTF) is a proprietary document file format developed by Microsoft in 19…
DokumentA shared object file, identified by the `.so` extension, is a dynamically linked library …
AusführbarA .pyo file is a compiled version of a Python source code file (.py). It's created when P…
AusführbarPickle is a Python-specific file format used for serializing and de-serializing Python ob…
DatenThe .app extension on macOS signifies an Application Bundle. This isn't a single file, bu…
AusführbarA TSV (Tab-Separated Values) file is a simple text-based format for storing tabular data,…
DatenThe .apks file extension represents an Android Package Set Archive. This archive format i…
ArchivA dylib file is a dynamically linked library used on macOS operating systems. It's analog…
AusführbarAPNG (Animated Portable Network Graphics) is a file format that extends the PNG (Portable…
BildHTML (HyperText Markup Language) is the standard markup language for creating web pages. …
DatenA DMG file is an Apple Disk Image file, a common format used on macOS to distribute softw…
ArchivA .bak file is a backup file, a common extension used to denote a copy of data created fo…
DatenReceiving a file you cannot open is one of the most common tech frustrations. Before you panic or assume the file is corrupted, follow these steps to identify the format and find the right application in minutes.
Look at the very end of the filename after the last dot. On Windows, enable Show file name extensions in File Explorer — Windows hides them by default. Note the exact extension, including double extensions like .tar.gz.
Enter the extension in the search box at the top of this page. You will get the full format name, who created it, and which category it belongs to. This alone often answers your question.
Each extension page lists free and paid applications for Windows, macOS, Linux, Android, and iOS. Many obscure formats open in free tools — .heic images open in the free CopyTrans HEIC plugin for Windows, for instance.
If installing new software is not an option, converting to a more common format often solves the problem. Each extension page links to practical conversion options — free online converters handle most transformations.
Renaming a file from .xyz to .jpg does not change what is inside it. The file will still fail to open correctly. Always look up the format first rather than guessing by renaming.
The most frequently encountered file types and the best free tools to open them on any platform.
.pdfPortable DocumentAdobe Acrobat Reader.docxWord DocumentLibreOffice Writer.xlsxExcel SpreadsheetLibreOffice Calc.pptxPowerPoint SlidesLibreOffice Impress.jpgJPEG ImageBuilt-in (all OS).pngPNG ImageBuilt-in (all OS).mp4MPEG-4 VideoVLC Media Player.mp3MPEG-3 AudioVLC / foobar2000.zipZIP ArchiveBuilt-in (Win/Mac/Linux).rarRAR ArchiveWinRAR / 7-Zip.heicApple HEIC ImageCopyTrans HEIC (Win).mkvMatroska VideoVLC Media PlayerPicking the wrong format can mean bloated file sizes, permanent quality loss, compatibility failures, or security risks. Here is why the choice deserves careful thought.
The same photograph saved as uncompressed .bmp might be 10 MB. As a .jpg it could be 500 KB — a 20× reduction. As .webp even smaller with no visible quality loss. Over thousands of files, format choice has a dramatic impact on storage costs and transfer speeds. Knowing which format offers the best compression for your content type is essential for anyone managing large media libraries.
Lossy formats discard data permanently on every save. Editing a .jpg and saving repeatedly degrades quality visibly over time — a phenomenon called generation loss. Lossless formats like .png, .tiff, and .flac preserve every bit of the original. For professional photography, audio mastering, or document archiving, choosing a lossless format ensures you never lose data you cannot recover.
Sending a .pages document to a Windows user who lacks Apple software is a guaranteed compatibility failure. Sending a .docx works for almost everyone. Before sharing any file, consider whether the recipient's system can open it. Open formats like .pdf, .csv, and .mp4 travel furthest. Proprietary formats add friction when crossing organisational or platform boundaries.
File extensions can be spoofed. A malicious file named invoice.pdf.exe — on a system hiding extensions — displays as invoice.pdf, tricking users into running an executable. Extensions like .exe, .bat, .vbs, .ps1, and .jar deserve extra scrutiny when received from unknown senders. Always verify the true format before opening files from untrusted sources.
One of the most important but least-discussed dimensions of file format choice is longevity. Proprietary formats — those controlled by a single company — can be discontinued, changed without notice, or locked behind paid software. If a company discontinues its product, files saved in that format may become inaccessible within years.
Open formats, by contrast, are documented publicly and can be implemented by anyone. .pdf was proprietary until Adobe released the specification to ISO in 2008; it is now an international standard (ISO 32000). .odt and .ods (OpenDocument) were designed from the start as open standards under the ISO/IEC 26300 umbrella.
For personal archives — family photos, personal documents, creative projects — using open formats is a form of digital preservation. Your descendants will be far more likely to open a .png or a .flac in thirty years than a proprietary editing project from today's most popular creative software.
The same extension can behave very differently depending on your platform. Here is what you need to know about format support on Windows, macOS, Linux, Android, and iOS.
Windows is the most permissive desktop OS for third-party software, meaning almost every format has a compatible application available. Built-in support covers .jpg, .png, .bmp, .mp4, .mp3, and .pdf (via Edge). Notable gaps include .heic (requires a free codec), .mkv with certain codecs (VLC fills this), and Apple formats like .pages. The Windows Registry maps extensions to applications — this is why changing an extension changes which app opens the file.
macOS has deep native support for Apple-ecosystem formats including .heic, .pages, .numbers, and .key. Preview handles a wide variety of image and document formats out of the box. macOS uses Uniform Type Identifiers (UTIs) under the hood — the OS can sometimes correctly identify a file even if the extension is wrong. Gaps include Windows-centric formats like .wma and .wmv, which require VLC or similar third-party software.
Linux distributions use MIME types to map formats to applications, giving users fine-grained control. Most distros ship with strong support for open formats: .odt, .flac, .ogg, .png, .webp. Proprietary formats like .docx and .xlsx are handled by LibreOffice; .mp4 by VLC. Linux excels at command-line conversion — tools like ffmpeg, ImageMagick, and pandoc convert between hundreds of formats in batch.
Android handles common media formats natively: .jpg, .png, .mp4, .mp3, .aac, and .pdf. Business formats like .docx and .xlsx are supported by Google Docs and Microsoft 365. Uncommon formats like .flac, .mkv, and .avi benefit from VLC for Android. Apple-only formats like .heic and .pages often require conversion before they are fully usable on Android devices.
iOS has deep support for Apple formats and the most common web formats. .heic, .jpg, .png, .pdf, .mp4, and .aac all work natively. Microsoft 365 and Google Workspace apps cover office documents. Audio format .flac gained native iOS support in iOS 11. Video files in unusual containers may still need VLC. The sandboxed nature of iOS means file management is more restricted than on desktop operating systems.
Converting a file from one format to another is sometimes necessary and often straightforward — but a few principles are worth knowing because a poor conversion can cause data loss you may not notice until it is too late.
Converting from a lossless format to a lossy one permanently discards data. Going from .png to .jpg introduces compression artefacts that cannot be undone. Going in the other direction — from .jpg to .png — does not restore the lost quality. Always convert from the highest-quality source you have and keep the original file.
For video files, changing the container (.avi to .mp4) without re-encoding the video stream is called remuxing — it is fast, lossless, and preserves quality. True transcoding re-encodes the video and always involves some quality loss unless you use a lossless codec. Tools like HandBrake and ffmpeg let you choose between remuxing and transcoding.
Converting .docx to .pdf usually produces excellent results. Going in the other direction — PDF to Word — is inherently imperfect because PDF is a presentation format, not a structured document format. Complex tables and multi-column layouts often need manual correction after conversion.
.heic.jpgShare iPhone photos with Windows or Android users who lack HEIC support.
Minor quality loss at default JPEG settings. Use 90%+ quality to minimise artefacts.
.pages.docxSend Apple Pages documents to Word users on Windows or Linux.
Good fidelity for most documents. Complex layouts may need minor adjustment.
.wav.mp3Reduce audio file size for streaming, podcasts, or sharing online.
Lossy. Use 256 kbps or higher to preserve most audible detail.
.mp4.webmOptimise video for web embedding without licensing concerns.
Slight variation depending on codec settings. Use VP9 for best results.
.docx.pdfDistribute documents with locked formatting that looks identical everywhere.
Excellent — near-perfect fidelity in most word processors.
.png.webpReduce image size on websites without visible quality loss.
Very good. WebP lossless beats PNG in size; WebP lossy beats JPEG in quality-per-byte.
.rar.zipShare archives with recipients who do not have WinRAR installed.
Lossless — no data change, possible slight size difference.
.csv.xlsxAdd formatting, formulas, and charts to plain comma-separated data.
Lossless for the data itself; formatting is added, not converted.
Getting the information you need takes four steps and under thirty seconds.
Type any extension — with or without the leading dot — into the search bar. The directory searches across 5,000+ entries instantly and returns exact matches first.
Each entry explains what the format is, who created it, what category it belongs to, and what the data inside represents in plain, accurate language.
The compatible software section lists free and paid applications for Windows, macOS, Linux, Android, and iOS — so you always know what to download.
If a format has better or more compatible alternatives, the entry links to them — helping you make an informed choice before converting or committing to a workflow.
Accurate information about file formats is harder to find than it should be. Many search results are outdated, vague, or exist primarily to promote specific software. This directory takes a different approach.
Every entry is researched from primary sources — official format specifications, ISO and IETF standards documents, developer documentation, and vendor release notes. We do not publish guesses, and we do not accept payment to promote specific software.
The database is maintained on a rolling basis. When a new format gains traction or an existing format receives a significant update, the relevant entries are reviewed and updated to reflect the current state of the ecosystem.
Information drawn from official specs, ISO standards, and vendor documentation — not Wikipedia summaries or blog posts.
We never link to fake repair tools, misleading download pages, or paid software presented as the only option.
Every description is written to be understood by a non-technical reader without sacrificing technical accuracy.
New formats added regularly; existing entries reviewed when specifications change or new software emerges.
The directory is available in multiple languages so users worldwide can access information in their native language.
MIME types, magic bytes, and version history are included for developers who need more than a plain-English summary.
Real feedback from professionals, students, and everyday users who rely on this directory.
"I was struggling to open a .ai file on my Windows PC. This site told me exactly which free software to use and explained what the format does. Saved me hours of frustrating searching."
"An incredibly useful reference. I use it daily when users send tickets about unknown file types. The compatibility table for each extension is particularly helpful."
"Clear, simple explanations with no confusing jargon. I finally understand the difference between RAR and ZIP, and why my lecturer sends .pages files I cannot open on Windows."
"The alternative-formats section is a hidden gem. Helped me convince a client to switch from a proprietary format to an open standard with solid reasoning I could share directly."
Answers to the questions we receive most often about file extensions and this directory.
Our database covers over 5,000 file types — from the most popular formats to the most obscure. Search now and get an instant, accurate answer.
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