Architects, engineers and drafters often need to show that a design existed before a tender, a planning lodgement or a dispute with a client. AutoCAD drawings carry more date information than most files, which helps, but it is all written by the software on your own computer. Here is what a DWG records, where that falls short, and what to freeze.
Short answer: AutoCAD stores creation and edit times in a DWG, but they are written from your own computer’s clock. To show a drawing existed before a tender, lodgement or dispute, save the exact DWG and a PDF set, and timestamp them with TimeBinder before you issue them. A TimeBind shows that the exact file existed no later than the recorded time and still matches its fingerprint. It doesn’t show who made it or what a court will make of it.
Disclosure: I’m Inna Hall, co-founder of TimeBinder, the file timestamping tool this guide uses. This page is general information, not legal advice.
Table of Contents
Where a DWG keeps its dates
- TDCREATE stores the local date and time the drawing was created, and TDUPDATE the local date and time of the last save. Both are stored inside the drawing as Julian date numbers (see Autodesk’s TDCREATE reference).
- TDINDWG stores the total editing time for the drawing.
- Drawing Properties (DWGPROPS) holds title, author, keywords and custom fields, plus a statistics tab showing those dates.
- Backup and autosave files. AutoCAD can keep a .bak copy of the previous save and write autosave .sv$ files at intervals.
- Plots. PDFs plotted from AutoCAD carry their own creation date, which you can check with our free file date and metadata inspector.
Why those dates are easy to challenge
TDCREATE and TDUPDATE use the local clock of whichever computer saved the drawing, and drawings are often started from templates or copied from earlier projects, so the dates can be confusing even without anyone changing them. File-system dates change when drawings are copied, emailed or moved between servers. A client or competitor only has to say the dates are unreliable for them to carry little weight.
What to freeze
| File | Why it matters |
|---|---|
| The DWG at each milestone | The design itself, with layers, blocks and dimensions |
| An eTransmit zip | Packs the drawing with its xrefs, fonts and plot styles, so the set opens complete |
| The PDF set you issue | What the client, council or builder receives |
| Sketches, calculations and briefs | Show how the design developed |
A simple routine
- Before issuing a drawing set or sending a concept, save and close the drawings.
- Run eTransmit to create one zip for the set, including xrefs.
- Plot or publish the PDF set you will issue.
- Open TimeBinder and TimeBind the eTransmit zip and the PDF set together (up to 10 files per TimeBind).
- Keep the certificate with the issued set. Make later changes in a new revision, not in the frozen files.
Which plan fits
The Free plan is $0 and gives you 1 Token a month. A Pooled TimeBind costs 1 Token, covers up to 10 files and is usually recorded within 24 to 48 hours, and often sooner, depending on Bitcoin network activity. An ASAP TimeBind costs 3 Tokens and gets its own Bitcoin transaction straight away. Checking a file is always free, and no credit card is needed for the Free plan.
If you TimeBind more often, Essential is US$20 a month for 5 Tokens ($4 per Token, against $5 pay-as-you-go) and Expert is US$50 a month for 15 Tokens (about $3.33 per Token). Paid plans replace the Free plan’s monthly Token, so Essential adds 4 Tokens for US$20 and Expert adds 14 for US$50. See pricing.
What a timestamp does and doesn’t do
TimeBinder anchors each file’s SHA-256 fingerprint to the Bitcoin blockchain and gives you a Proof of Time Certificate. That is verifiable evidence of when a file existed: it shows the file existed no later than the anchor time, and any later change to the file is detectable. Your file is hashed in your browser and never uploaded. ASAP TimeBinds can be checked independently from the certificate and the Bitcoin blockchain; Pooled TimeBinds are verified through TimeBinder.
It doesn’t show who created the file, whether its contents are true, or whether AI was used to make it, and it can’t tell you how a court or anyone else will treat it. It also doesn’t cover versions you didn’t TimeBind. Pooled TimeBinds are verified through TimeBinder; ASAP TimeBinds can also be verified independently from the certificate and the Bitcoin blockchain. Ownership of drawings is usually set by your contract or appointment, not by a timestamp. See also proving a 3D CAD model existed, architectural design timestamping and design file timestamping.
Frequently Asked Questions
Does a DWG file record when it was created?
Yes. AutoCAD stores system variables such as TDCREATE (when the drawing was created) and TDUPDATE (when it was last saved), both in local time. You can see them with the TIME command or in Drawing Properties. They come from the computer’s clock, so they are context rather than independent evidence.
What is TDINDWG?
It is the total editing time AutoCAD has recorded for the drawing. It can help show that real work went into a drawing, but like the other variables it is stored inside the file and depends on the software and the computer.
What about xrefs?
External references live in separate files. Use eTransmit to package the drawing with its xrefs, fonts and plot styles into one zip, and TimeBind that zip.
Should I timestamp the DWG or the PDF?
Both. The DWG shows the design itself, and the PDF plot is what clients and authorities usually receive, so its fingerprint is easiest to match later.
Is my drawing uploaded?
No. TimeBinder hashes files in your browser and only the fingerprint is anchored to Bitcoin, so confidential plans stay with you.
Plan details were checked against timebinder.io/pricing on 29 October 2026.
