What is the PDX file format?
The .pdx file is a pointer file used by Adobe Acrobat's Catalog feature to locate a full-text search index built from a collection of PDF documents. Adobe introduced the format with Acrobat 2.0 in the early 1990s, and it remains supported in Acrobat Pro DC and Acrobat 2024.
A .pdx file is a small plain-text document - typically under 2 KB - that lists paths to the accompanying .idx index files and includes Boolean flags controlling catalog behavior such as case sensitivity and number indexing. The .idx files, stored in an adjacent support folder, hold the actual inverted-index data built from scanning the target PDFs. The .pdx is only a manifest; moving it without the support folder breaks the index entirely.
To create a catalog, Acrobat Pro's Full Text Index with Catalog tool (Tools > Index) scans a folder hierarchy of PDFs, builds the .idx data, and writes the .pdx manifest. Users then load the .pdx in Acrobat's Search panel (Shift+Ctrl+F) to run fast full-text queries across hundreds or thousands of documents without opening each file.
A related variant, .bpdx, is used for scripted batch operations to automatically rebuild, update, or purge a catalog index.
Note: the .pdx extension is also used by Corel Paradox for a secondary database index - an entirely unrelated format.
Security & safety
RISK: LOWPDX files are plain text and cannot execute code or embed malware. The only risk is that a crafted PDX pointing to UNC or external paths could cause Acrobat to access network resources when loading the catalog. On modern Acrobat this is mitigated by path validation.
Format details
in a nutshell- Corel Paradox Database Secondary Index - Paradox (dBASE-style relational database) uses .pdx for secondary index files associated with .db table files; unrelated to Adobe Acrobat.
- PrintShop Mail Data Extension - Some versions of PrintShop Mail use .pdx for variable-data printing data extensions.
Programs that open PDX files
Windows2 apps
Adobe Acrobat Pro
Paid Tools > Index > Full Text Index with Catalog - load the PDX to search, rebuild, or update the catalog.
Notepad / any text editor
Open-source Open to inspect the file paths and flags stored in the PDX manifest. Useful for diagnosing broken catalog paths. 
macOS1 app
Adobe Acrobat Pro
Paid Tools > Index > Full Text Index with Catalog - load and manage the PDX catalog. Technical details
deep spec| Format | Plain text (ASCII/UTF-8); proprietary list format documented by PRONOM as fmt/449, version 3.2 |
| Role | Pointer and manifest only - lists paths to the real index data held in accompanying `.idx` files |
| File size | 200 bytes - 2 KB (pointer file only; `.idx` files in the support folder hold the actual index data) |
| Boolean flags | Control catalog behavior: case sensitivity, number inclusion, and other indexing options |
| Support folder dependency | `.pdx` must remain co-located with its named support folder; moving one without the other breaks the index |
| Index scope | Catalogs a folder hierarchy of PDF documents for Acrobat full-text search |
| Search access | Loaded in Acrobat's Search panel (`Shift+Ctrl+F`) to query large PDF collections without opening individual files |
| Batch variant | `.bpdx` format used for scripted catalog rebuild, update, and purge operations |
| Creation tool | Acrobat Pro Full Text Index with Catalog tool (Tools > Index menu) |
| Platform | Windows and macOS (Acrobat Pro) |
| Name collision | `.pdx` also used by Corel Paradox for secondary database index files - an entirely unrelated format |
| Typical use case | Offline document repositories such as legal archives and technical documentation libraries requiring fast full-text search |
| Released | Early 1990s (Acrobat Catalog feature, Acrobat 2.0 era) |
| Latest version | Adobe Acrobat Catalog; current in Acrobat DC / Acrobat 2024 |
| Specification | helpx.adobe.com |
PDX conversions
Community Q&A
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