Format reference
What each format is, what it's good at, and what it isn't. Use this as a cheat sheet when you're picking a target format.
PDF — Portable Document Format
The default for finalized documents. PDF locks layout, fonts, and pagination so the file looks identical on every device. Good for résumés, contracts, invoices, reports, and anything you're sending out for review or print. Bad for editing — PDFs aren't structured documents, so editing usually means converting to DOCX first. Need to split pages or merge multiple PDFs? Try our PDF Splitter and PDF Merger tools. Too big to email? Shrink large PDFs with our PDF compressor — typically 50-80% smaller with no visible quality loss.
MIME: application/pdf · Extension: .pdf · Best target for: finalizing, sending, printing.
DOCX — Microsoft Word
The standard word-processing format since 2007. Editable in Word, Google Docs, LibreOffice, Pages, and basically every other word processor. Carries fonts, headings, tables, images, and tracked changes. Use it for documents you'll keep editing; switch to PDF when you're done.
MIME: application/vnd.openxmlformats-officedocument.wordprocessingml.document · Extension: .docx · Best target for: editing.
XLSX — Microsoft Excel
The standard spreadsheet format since 2007. Editable in Excel, Google Sheets, LibreOffice Calc, Apple Numbers. Carries formulas, charts, multiple sheets, merged cells, conditional formatting, and cell colors. Convert XLSX to CSV to extract the first sheet as plain rows for scripts and databases, XLSX to JSON to feed spreadsheet data to scripts and APIs, or XLSX to PDF to lock the layout for review and print.
MIME: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet · Extension: .xlsx · Best target for: editing, formulas, multi-sheet workbooks.
CSV — Comma-Separated Values
Plain-text tabular data, one row per line. The lingua franca of scripts, databases, BI tools, and data pipelines. No formulas, no formatting, no multiple sheets — just values. Convert CSV to XLSX to hand a script's output to a colleague who lives in Excel, or CSV to PDF for a printable table without round-tripping through a spreadsheet app.
MIME: text/csv · Extension: .csv · Best target for: scripting, data science, version control.
PPTX — Microsoft PowerPoint
The standard presentation format since 2007. Used for creating slide shows, pitches, and school presentations. Convert PPTX to PDF to guarantee your formatting stays intact on any projector, or PPTX to JPG / PPTX to PNG to get clean slide preview images.
MIME: application/vnd.openxmlformats-officedocument.presentationml.presentation · Extension: .pptx · Best target for: slide shows, pitches.
MD — Markdown Document
Lightweight plain-text formatting syntax used heavily by developers, writers, and technical editors. Write in clean plain text and convert Markdown to HTML for the web, Markdown to PDF for reading/distribution, or Markdown to DOCX to open in Microsoft Word.
MIME: text/markdown · Extension: .md · Best target for: distraction-free writing, documentation.
TXT — Plain text
Just characters, no formatting. Useful when you want the words and nothing else — for grep, copy-paste into a code editor, feeding into a script, or stripping every trace of layout from a document. Pair with OCR to pull text out of an image.
MIME: text/plain · Extension: .txt · Best target for: stripping formatting, scripting.
HTML — Web document
The format the web is built on. Good for content meant to be read in a browser, embedded in an email, or processed by a static-site generator. Convert HTML to PDF to snapshot a page exactly as it looks today.
MIME: text/html · Extension: .html, .htm · Best target for: web display, archiving a webpage.
SVG — Scalable Vector Graphics
Vector-based XML graphic format ideal for web design. Scalable to any size without loss of resolution. Convert SVG to PNG or SVG to JPG for universal web display, or PNG to SVG / JPG to SVG to vectorize raster logos. Need a favicon? Convert SVG to ICO or PNG to ICO.
MIME: image/svg+xml · Extension: .svg · Best target for: icons, logos, vector design.
EPUB, MOBI, & AZW3 — eBook formats
The standard formats for e-readers. EPUB is open-standard and universally accepted by Kobo and Apple. MOBI and AZW3 are Kindle-specific proprietary formats. Convert between them using our eBook converters: EPUB to PDF, EPUB to MOBI, MOBI to EPUB, and AZW3 to EPUB.
MIME: application/epub+zip / application/x-mobipocket-ebook · Extension: .epub, .mobi, .azw3 · Best target for: eBooks, digital publishing.
JSON, YAML, & XML — Data & Developer
Structured configuration and exchange data standards. JSON is standard for APIs, YAML is popular for human-readable configurations, and XML is used in legacy Enterprise setups. Convert easily using JSON to CSV, CSV to JSON, JSON to YAML, and XML to JSON.
MIME: application/json / application/x-yaml / application/xml · Extension: .json, .yaml, .xml · Best target for: config storage, data APIs.
ZIP, RAR, & 7Z — Archives
Compression envelopes packaging one or more files. ZIP is universally supported. RAR and 7Z offer superior compression bitrates but require specialized extraction. Transcode them to standard ZIP via RAR to ZIP and 7Z to ZIP.
MIME: application/zip / application/vnd.rar / application/x-7z-compressed · Extension: .zip, .rar, .7z · Best target for: archive packaging, attachment downloads.
MP4 — Video Clip
Standard modern digital video format. Used heavily for streaming, social media uploads, and screen recordings. Convert MP4 to GIF to create a high-quality loop, or MP4 to MP3 to extract the soundtrack.
MIME: video/mp4 · Extension: .mp4 · Best target for: video playback, screen captures.
MP3 & WAV — Audio formats
Standard audio formats. MP3 uses compressed lossy encoding (tiny files, broad compatibility), while WAV stores raw waveform audio (lossless, large files, perfect for editing). Convert between them easily using our audio converter.
MIME: audio/mpeg / audio/wav · Extension: .mp3, .wav · Best target for: audio playback, podcasts, voice notes.
Picking the right format
- For final, polished documents: PDF.
- For documents you'll keep editing: DOCX.
- For slideshows and presentation decks: PPTX.
- For plain text writing and documentation: Markdown.
- For vector assets, web icons, and logos: SVG.
- For eBooks: EPUB (Kindle accepts EPUB now too!).
- For structured data exchange: JSON.
- For configuration and orchestration files: YAML.
- For photographs on the web: WebP first, JPG as fallback.
- For video clips and screencasts: MP4.
- For audio tracks and podcasts: MP3.
See where Formatly fits.
Formatly is built for quick no-signup jobs under 20 MB, not enterprise conversion coverage. These comparisons keep the tradeoffs explicit.