History Lesson: What Is a .odp File? Why PowerPoint Opens It but Slides Shift

What is a .odp file?

A .odp file is the presentation member of the OpenDocument Format (ODF), the open standard for office files that also covers .odt text documents, .ods spreadsheets, and .odg drawings. It is the native slide format of LibreOffice Impress and Apache OpenOffice Impress, Calligra Stage uses it too, and Microsoft PowerPoint can open and save it. Its official media type is application/vnd.oasis.opendocument.presentation. A presentation template uses .otp, and a .fodp is the “flat” variant: the same XML in one uncompressed file instead of a ZIP.

Why does PowerPoint open it, but the slides look different?

Because PowerPoint does not edit OpenDocument directly. It reads the package, maps every slide, master, shape, and effect into its own model, and writes OpenDocument again only when you save. Microsoft’s support page is candid: an OpenDocument presentation opened in PowerPoint “might not have the same formatting as it did in the original application.” Its feature table lists themes as not supported and masters, layouts, and placeholders as only partly supported. Entrance and exit animations that ODF cannot express are changed to a plain Appear or Disappear; color and scaling animations, animation and transition sounds, and the Blinds, Cut, Strips, Comb, and Newsflash transitions are not supported. Headers and footers become ordinary text boxes, comments and Autofit are not supported, and WordArt keeps its text and base color but loses its effects.

Fonts cause the rest. A slide usually records the name of a font, not the font itself. LibreOffice can embed fonts in a deck, but only if someone ticks “Embed fonts in the document” under File > Properties > Font, and font licences can forbid it. When the PC opening the file lacks a font, a substitute with different letter widths takes its place, so a title that fitted on one line wraps onto two, or bullet text spills past the bottom of its box.

1990s–2002: StarImpress, Sun, and OpenOffice.org Impress

The family starts with Star Division, founded in 1985 in Lüneburg, Germany, by Marco Börries. Its StarOffice suite gained a presentation program, StarImpress, by the StarOffice 3.x and 4.x era; the UK National Archives’ PRONOM registry has records for StarOffice Impress 3.x and 4.x files, and a May 1998 LinuxFocus review of StarOffice 4.0 described its presentation maker as similar to PowerPoint. Those decks were binary files; StarImpress 5.x saved .sdd.

Sun Microsystems bought Star Division in August 1999, and on 19 July 2000 announced it would release the StarOffice source code as OpenOffice.org, a project that would also coordinate XML-based file formats. OpenOffice.org 1.0 arrived on 1 May 2002, and its Impress saved .sxi: a ZIP package of XML parts instead of a binary file. That package design is the direct ancestor of .odp — see History Lesson: What Is a .sxi File?.

2005: OpenDocument becomes a standard

The package went to OASIS, the Organization for the Advancement of Structured Information Standards, a non-profit consortium for open technical standards. Its OpenDocument committee first met on 16 December 2002, and ODF 1.0 — with presentations as one of its document types — became an OASIS Standard on 1 May 2005. OpenOffice.org 2.0, released on 20 October 2005, made OpenDocument the default, so Impress started saving .odp instead of .sxi. ISO and IEC published the standard as ISO/IEC 26300:2006 on 30 November 2006. Later versions followed: ODF 1.1 in February 2007, ODF 1.2 in September 2011, ODF 1.3 in April 2021, and ODF 1.4, approved on 6 October 2025.

How the bytes work: a ZIP of XML, one draw:page per slide

Open a .odp in a hex viewer and the first two bytes spell PK, the signature of a ZIP archive. The ODF packaging rules require a small file named mimetype to come first, stored uncompressed, containing only application/vnd.oasis.opendocument.presentation, so software can recognize the deck without unpacking it. After it come content.xml (the slides), styles.xml (master slides and styles), meta.xml (author and dates), settings.xml, and META-INF/manifest.xml, the list of every part. XML, short for Extensible Markup Language, is plain text built from tags. Photos are not stuffed into the XML: LibreOffice stores them as separate files in a Pictures folder inside the package, and the standard asks for a small preview of the first slide at Thumbnails/thumbnail.png.

Inside content.xml, an office:presentation element holds one draw:page element per slide, each with a unique name such as page1, and a reference to its master page in styles.xml. That draw: prefix is a clue: the Library of Congress’s format description notes that each slide is essentially an OpenDocument drawing. Text boxes, pictures, and shapes sit inside the page as frames; speaker notes live in a presentation:notes element; and animations borrow elements from SMIL, the W3C’s Synchronized Multimedia Integration Language, under the anim: and smil: prefixes. Every one of those pieces has to be mapped onto a PowerPoint equivalent when the deck crosses over.

PowerPoint and OpenDocument, from 2009 to today

PowerPoint gained built-in OpenDocument support with Microsoft Office 2007 Service Pack 2, released on 28 April 2009, which read and wrote ODF 1.1. The Library of Congress notes that Office has supported direct editing of ODF 1.2 presentations since Office 2013, and Office 2021 moved on to ODF 1.3. That is real support — PowerPoint’s File > Open dialog even has an OpenDocument Presentation filter — but it remains a translation between two different models of a slide, not a shared native format.

LibreOffice, governments, and why .odp files are still on disks in 2026

Oracle bought Sun in 2010. On 28 September 2010 community developers announced The Document Foundation and LibreOffice, whose Impress is a fork of OpenOffice.org Impress, and on 1 June 2011 Oracle gave the OpenOffice.org code to the Apache Software Foundation, home of Apache OpenOffice. Both still save new decks as .odp by default. Public bodies pushed the format further: Massachusetts set an OpenDocument policy for its agencies in September 2005, the UK government chose ODF for sharing and collaborating on documents on 22 July 2014, and in March 2026 Germany’s IT planning council named ODF in its Deutschland-Stack standards.

So .odp decks pile up wherever the free suites are the default: school and university computers, charities, churches and clubs, Linux laptops, conference talks, and offices that never bought Microsoft Office. Many are now legacy files — made in a suite that is no longer installed, set in fonts that only came with an old system, or needed as .pptx by a colleague who has never seen an OpenDocument file.

When you need PPTX or PDF instead

Renaming .odp to .pptx does nothing: the parts inside are still OpenDocument XML, and .pptx is a different standard, Office Open XML, published as ISO/IEC 29500 in November 2008. A real conversion reads the OpenDocument slides and writes a new file. Pick PPTX when someone needs to keep editing in PowerPoint, PDF when the slides must look the same everywhere or be kept for the record, and HTML when they just need to be read in a browser. Then click through the result and check fonts, animations, transitions, and headers or footers.

Legacy File Converter opens .odp and flat .fodp presentations on your own Windows PC and saves them as PPTX, PDF, or HTML — nothing is uploaded, which matters when the slides hold unreleased plans or student work. For the generation before OpenDocument, see History Lesson: What Is a .sxi File?; for PowerPoint’s own lineage, see History Lesson: PowerPoint (.ppt); and for Apple’s slide format, see History Lesson: What Is a .key File?.