What is an XER file?
An XER file is the native export format of Oracle Primavera P6. It is a plain-text file made of tab-delimited tables: projects, WBS, activities (tasks), relationships, calendars and resources. P6 writes one when you choose File > Export > Primavera PM (XER).
The file carries the schedule's logic and dates, not the P6 program, its layouts or its reports. A PMXML file (.xml) holds the same kind of schedule data in XML form, and this viewer opens both.
One XER file can contain several projects. If yours does, the viewer asks which project to open.
How to open an XER file without Primavera
You only need a modern browser.
- Get the .xer or P6 .xml file from your planner, or export it from P6 (File > Export).
- Drop it on the viewer above, or choose the file. You can also open the built-in sample to try the tool first.
- Switch between the Activities table, the WBS tree and the Gantt. Use the filters to show only critical, not started or in-progress activities, a WBS branch or a date range.
- Click any activity to see its predecessors and successors with relationship type and lag.
- Download the activity table as CSV, or print the Gantt and choose "Save as PDF".
How to read a construction schedule
A P6 schedule looks dense, but a few ideas explain most of it.
- WBS (work breakdown structure)
- The tree that breaks the project into areas, phases or trades. Every activity sits under one WBS node, so you can roll progress and dates up from activities to phases.
- Original and remaining duration
- Original duration is the planned length of an activity in working days. Remaining duration is what is left to do as of the data date.
- Data date
- The date the schedule was last updated with progress. Work before it should show actual dates; work after it is still forecast.
- Total float
- How long an activity can slip without pushing the project finish date. An activity with zero or negative float has no slack left.
- Critical path
- The chain of activities with no float. A delay to any of them delays the finish. This viewer marks an activity critical when its total float is 0 or less and it is not yet complete. P6 can also define critical activities by longest path, so the flag can differ from P6's if your file is set up that way.
- Relationships and lag
- Finish-to-start (FS) is the common case. Start-to-start (SS), finish-to-finish (FF) and start-to-finish (SF) overlap work. Lag adds a delay between two linked activities; a negative lag is a lead.
Do you actually need a P6 licence?
Often not, if all you need is to look. Site managers, quantity surveyors, consultants and clients regularly receive a schedule only to read it, check a milestone or print a look-ahead. A viewer is enough for that.
You do need P6 (or another scheduling tool) when you want to change the schedule: edit logic, add activities, update progress and reschedule, set baselines, level resources, or run what-if scenarios. This viewer is read-only. It does not recalculate dates, edit or save back to XER, show baselines or resource curves, or reproduce P6 layouts.
For contractual decisions such as extension-of-time claims, always confirm against the master schedule in P6.
Your schedule never leaves your device
The file you choose is read by your browser and parsed by a script running on your own device. It is not uploaded, stored on a server or sent to Arkan. You can confirm this in your browser's developer tools: opening a file makes no network request.
Page analytics only record that a file was opened, with its type (XER or XML) and a rough size range. They never include the file name, activity names or any schedule content.
If you use the optional email requests below the viewer, only the email and name you type are sent, not your schedule.
What this viewer reads
Primavera P6 XER exports and P6 XML (PMXML) exports, up to 150 MB. From them it reads projects, WBS, activities, durations, dates, total and free float, status and percent complete, relationships with type and lag, calendars and resource assignments.
Text is read as UTF-8 and falls back to Windows-1252, which is how many XER files are written. If a file uses another code page, some characters may look wrong.
Microsoft Project (.mpp), Excel and PDF schedules are not supported.
Oracle and Primavera are trademarks of Oracle. Arkan is not affiliated with Oracle; this tool is compatible with Primavera P6 files.