AI File (.ai): What It Is and How to Open It

The basics

What is an AI file?

An AI file is the native document of Adobe Illustrator, the vector drawing app Adobe launched for the Mac in 1987. Where a PNG or JPG stores pixels, an AI file stores shapes: paths with anchor points and Bézier curves, fills, strokes and live text. That's why logos, icons, illustrations, packaging and type designs are drawn in Illustrator and delivered as .ai: the artwork can be enlarged to a billboard without losing sharpness, and every element stays editable.

Besides the drawing itself, an AI file keeps what a designer needs to keep working: layers, several artboards (separate canvases in one file), symbols, swatches, live effects such as drop shadows, and placed images, either embedded or linked from other files.

It's a working file, not a delivery format. Like a PSD for Photoshop, it's meant to be reopened in the app that made it. For the web, export SVG or PNG; for print, a PDF.
It's a PDF inside. Since Illustrator 9 in 2000, an AI file is a PDF with Illustrator's data added. That's why PDF viewers can often show one.
It isn't an open format. Adobe doesn't publish a specification for the native data. Other apps rely on the PDF part, so what they can edit is the artwork, not Illustrator's live features.

Anatomy

What's inside an AI file

There's no sample file on this page: only Adobe Illustrator writes .ai files. The outline below comes from the UK National Archives' PRONOM registry, which identifies AI files by these markers, Adobe's documentation of Illustrator's save options and the PDF specification. A current AI file is two things in one: an ordinary PDF of the artwork for other programs, and Illustrator's own editable data hidden inside it.

A PDF-compatible .ai file (structure outline)

artwork.ai  (Illustrator 9 or later, saved with
"Create PDF Compatible File"; structure outline)

%PDF-1.x                          a PDF header, so the file
%âãÏÓ                             starts like any PDF

1 0 obj << /Type /Catalog … >>    ordinary PDF objects:
… << /Type /Pages … >>            the catalog, the page tree,
… << /Type /Page                  one page per artboard
     /MediaBox [ … ]
     /Contents …                  the artwork as PDF drawing code,
     /Resources …                 with fonts and images
     /PieceInfo <<
       /Illustrator << /Private … >>
     >> >>                        → Illustrator's private data

… AIPrivateData …                 the native artwork (PGF) in
                                  numbered streams, compressed
                                  when "Use Compression" is on;
                                  PDF viewers skip all of it

xref … trailer … %%EOF            the PDF's index and end

Illustrator 8 and older: PostScript text instead
%!PS-Adobe-3.0
%%Creator: Adobe Illustrator(R) …
%%BoundingBox: …
%AI5_FileFormat …                 Illustrator's own comments

1%PDF-1.x
A PDF header
Since Illustrator 9, an AI file starts like any PDF. PRONOM's signature for Illustrator 9 looks for %PDF-1., then AIPrivateData, then Illustrator's PostScript comments further on.
2/Type /Page … /Contents
The PDF part
The artwork as standard PDF drawing instructions, one page per artboard, with the fonts and images it needs. This is what Acrobat, browsers and other PDF viewers show. It's only written when Create PDF Compatible File is ticked.
3/PieceInfo << /Illustrator …
A hook for private data
PDF lets an application attach its own data to a page through a PieceInfo dictionary, and viewers that don't recognise it skip it. Illustrator uses an entry called Illustrator to point to its private data.
4AIPrivateData
Illustrator's own data
The real working file: every path, layer, artboard, live effect, symbol and text frame as Illustrator understands it, in Adobe's native format, PGF. Illustrator reads this part and ignores the PDF part. It's split across numbered streams and compressed when Use Compression is on.
5xref … trailer … %%EOF
The PDF's index
As in any PDF, a table of where each object starts and a trailer pointing to the root. That's what lets a PDF reader open the file at all.
6%!PS-Adobe-3.0
Illustrator 8 and older
Before 2000, AI files were PostScript text, close relatives of EPS, with Illustrator's own %AI5_… comments. Illustrator 9 files also carried such a PostScript copy in their private data.

Under the hood

How an AI file stores the artwork twice

Adobe's own documentation says that AI files use both PDF and PGF formats. PGF is Illustrator's native data, which only Illustrator reads. The PDF is a standard rendering of the same artwork for everyone else. When you save, Illustrator's Illustrator Options dialog decides what goes in:

Option	What it does	Effect on the file
Create PDF Compatible File	Writes the PDF part next to Illustrator's data, so other apps can open, place and print the file. InDesign needs it to place an AI file	Bigger, because the artwork is stored twice; linked images are embedded in the PDF part
Embed ICC Profiles	Stores the document's colour profile	A little bigger, colours more predictable
Use Compression	Compresses Illustrator's own data	Smaller, a little slower to save
Include Linked Files	Copies linked images into Illustrator's data	Can be much bigger

Generations of the AI format
Illustrator version	What an .ai file is
1.0 to 8 (1987–1998)	PostScript text with Illustrator comments, compatible with EPS. Files start `%!PS-Adobe-3.0`
9 (2000)	A PDF holding the artwork, plus a PostScript copy of the Illustrator data
Later versions, up to Illustrator 2026	A PDF (if PDF compatibility is on) with Illustrator's native data as private data, optionally compressed

The reverse also exists: a PDF saved from Illustrator with Preserve Illustrator Editing Capabilities carries the same private data, so Illustrator can reopen it as editable artwork. Edit such a PDF in Acrobat, though, and the PDF part and the hidden Illustrator data no longer match.

Comparison

AI vs EPS, PDF and SVG

	AI	EPS	PDF	SVG
Made for	Editing in Illustrator	Placing artwork in print layouts	Print and sharing	Web and apps
Keeps live Illustrator features	Yes	No	Only with Preserve Illustrator Editing Capabilities	No
Transparency	Yes	No (flattened)	Yes	Yes
Several artboards	Yes	No	As pages	No
Opens in a browser	No, it downloads	No	Yes	Yes
Open standard	No	Published, frozen	ISO 32000	W3C

Sending to a designer who uses Illustrator: the .ai file, with linked images and fonts, or packaged with File, Package.
Sending to a printer: a print-ready PDF, unless they ask for AI or EPS.
For a website: an SVG for the logo and a PNG for anything that needs a fixed pixel size.
For someone without Illustrator: a PDF, which shows the artwork exactly and keeps it vector.

How to

How to open an AI file without Illustrator

Inkscape (free, Windows, macOS, Linux) imports AI files from Illustrator 9 onwards through its PDF importer. You get the artwork as editable paths and text, but not Illustrator's live effects, symbols or appearance settings.
Affinity Designer and Affinity Photo import AI files, including files with several artboards. They can't save .ai.
Any PDF viewer can show a PDF-compatible AI file, because the file is a PDF. If the viewer goes by the extension, open the file from inside the viewer, or rename a copy to .pdf.
Illustrator 8 and older files are PostScript, not PDF, so PDF viewers can't show them and Inkscape, which supports AI 9.0 and newer, can't import them.
In a browser: browsers don't display .ai, so a link to one downloads it.
On the command line: because the file is a PDF, pdftoppm -png -r 150 artwork.ai page or Ghostscript turns each artboard into a PNG.

Converting AI to SVG, PDF or PNG

In Illustrator, use File, Export, Export As for SVG and PNG, and File, Save a Copy, Adobe PDF for PDF. Without Illustrator, import the file into Inkscape or Affinity and export from there, then check gradients, effects and text, which may have been simplified.

Troubleshooting

Common AI file problems

"This is an Adobe Illustrator File that was saved without PDF Content." You opened the file in something other than Illustrator, and it was saved with Create PDF Compatible File turned off. There is no PDF part to show, only this message. Reopen it in Illustrator and save it again with the option on, or ask the sender for a PDF.
Text in the wrong font, or a missing-font warning. Illustrator needs the fonts installed to edit text; the PDF part's embedded fonts aren't enough. Install the fonts, or ask for a version with text converted to outlines.
Missing images. Placed images were linked, not embedded, and the linked files didn't travel with the AI file. Ask for the links too, or a packaged folder.
It looks right in Illustrator but different elsewhere. Other apps read the PDF part, which stops matching Illustrator's data if someone edited the file in Acrobat or another PDF tool, or they approximate effects they don't support. Trust Illustrator's view, or export a fresh PDF.
The file is huge. The artwork is stored twice when PDF compatibility is on, and embedded images and raster effects add up. Turning off Create PDF Compatible File, using compression and linking big images shrink it, at the cost of compatibility.

Security

What an AI file can give away

An AI file holds the whole working document, not just what the PDF part shows. Before sending one outside your team, check for:

Hidden layers and objects, and artwork placed off the artboards: rejected logo versions, client notes, other designs.
Embedded images at full resolution, even if they appear cropped or masked.
Metadata: author names, software versions and edit dates in the document's XMP data.
Old content in the private data, if a tool edited only the PDF part. What a PDF viewer shows may not be everything the file contains.

AI files don't carry macros the way Office documents can. The risk is bugs in the software that reads them: like any complex format parser, Illustrator and PDF libraries receive security updates, so keep them current. Pre-2000 AI files are PostScript, with the same risks as EPS when a server renders them with Ghostscript.

To share a design without its working layers, send a PDF saved without Preserve Illustrator Editing Capabilities, or an SVG or PNG export, rather than the .ai file.

Sample files

There are no sample AI files on this page yet. To make one for testing, save any artwork from Adobe Illustrator with File › Save As and choose Adobe Illustrator (ai); tick Create PDF Compatible File to test PDF viewers, or untick it to see what other apps show without the PDF part.

Put it online

Have an AI file? Give it a link.

Drop an Illustrator file on 99helpers and it gets its own link. Browsers can't display .ai files, so anyone who opens the link downloads it for Illustrator, Inkscape or Affinity; upload a PDF or PNG next to it so people without those apps can see the design.

Put an AI file online

Questions

AI files, frequently asked

What is an AI file?

The native file of Adobe Illustrator: a vector drawing with its layers, artboards, text and effects. Since Illustrator 9 (2000), it is a PDF with Illustrator's own editable data inside.

How do I open an AI file without Illustrator?

Import it into Inkscape (free) or Affinity Designer, or open it in a PDF viewer to look at it, renaming a copy to .pdf if needed. This works when the file was saved with Create PDF Compatible File on.

Why does my AI file say "saved without PDF content"?

It was saved with Create PDF Compatible File turned off, so only Illustrator can read it. Open it in Illustrator and save again with the option on, or ask for a PDF.

Is an AI file the same as a PDF?

Not quite. A PDF-compatible AI file contains a complete PDF, which is what other apps show, plus Illustrator's private data, which is what Illustrator edits. A PDF saved from Illustrator can likewise carry that data if Preserve Illustrator Editing Capabilities is on.

What's the difference between AI and EPS?

AI is Illustrator's working format, PDF-based, with transparency, layers and artboards. EPS is an older PostScript format for placing one picture in a print layout, without transparency. Illustrator files before version 9 were close to EPS.

How do I convert AI to SVG or PNG?

In Illustrator, use File, Export, Export As. Without Illustrator, import the file into Inkscape or Affinity and export from there.

Can a browser open an AI file?

No. Browsers don't display .ai files, so a link to one downloads it. Export a PDF, SVG or PNG to show the design in a browser.

Related formats

Other file types explained

EPS file PDF file SVG file PSD file SVGZ file PNG file All file types

Keep going

Host an AI file

Put an Illustrator file online at its own address.

Share an AI file

Send an Illustrator file as a link instead of an attachment.

Sources

Last reviewed 27 October 2026.