October 27, 2026
How to Prove When You Wrote Down an Idea Before You Share It
Turn notebook pages into one PDF, stamp it with a date nobody can backdate, and send it. Five steps in one browser tab, and the proof still matches later.
You have spent three months filling a notebook with sketches for a folding bike rack, and on Thursday you are meeting a small manufacturer who might build it. They have asked to see the drawings beforehand. You are happy to send them, but a quiet thought keeps coming back: once those pages leave your hands, what shows that you drew them first, and when?
The usual answers are weak. The photo dates on your phone can be edited in a few taps. Emailing the scans to yourself puts the date in your mail provider's hands. What you want is a way to prove when you wrote down an idea that a stranger can check without trusting you: a cryptographic timestamp, recorded in the Bitcoin blockchain, tied to the exact file you send.
Getting there from nine phone photos takes five tools, and the order matters more than any one of them. Everything runs in one browser tab, the pages never leave your computer, and the only things you download are the two files you will keep.
The chain at a glance
- Convert the iPhone photos to JPG so the rest of the chain can open them
- Turn the sideways pages upright
- Bind the pages into one PDF, in notebook order
- Shrink it for email, and download this copy, the one you will send
- Stamp that exact file and keep the proof beside it
Step 1: Get the photos out of HEIC
An iPhone saves photos as HEIC by default. It is an efficient format, but plenty of software still can't read it, including the rotation tool in the next step. So the first job is plain conversion.
Drop all nine photos into Image to JPG. Set Quality to High: handwriting has thin lines and fine shading, which low quality turns to mush. Then open Show advanced options, tick Resize (longest side) and choose 2560. A modern phone shoots around 4000 pixels on the long edge, far more than a notebook page needs, and every later step runs faster on smaller images. At 2560 your pencil strokes stay sharp. Press Convert 9 images to JPG.
Don't download the results. Rotate Image isn't in the suggested shortlist under Send to another tool, so open Other compatible tools and pick it there.
Step 2: Stand the sideways pages up
Three of your nine pages will probably come through lying on their side. When a phone is held flat above a desk, its motion sensor can't tell which edge is up, so it guesses, and it often guesses wrong.
In Rotate Image you can fix them one at a time with the arrows on each thumbnail. There is a quicker way. A notebook page is taller than it is wide, so any page that comes through sideways is wider than it is tall. Set Apply to to Landscapes, then press Right 90°: only the sideways pages turn, and the upright ones are left alone. Check the thumbnails. If one ended up upside down, give it two more turns with its own arrow. The summary line tells you how many images will be rotated, so you can confirm it matches the number of sideways pages.
Leave Output format on Keep original and press Rotate & download. Despite the button's name, nothing downloads yet. You land on the result screen. Open Other compatible tools again and choose JPG to PDF.
Step 3: Put the pages in notebook order
Your phone named the photos in the order you took them, which is rarely the order of the notebook. You probably shot the page you were proudest of first.
In JPG to PDF, drag the thumbnails into the right sequence. This is the last point where the order is easy to change. Keep Page size on A4 (or Letter if that is your paper), Orientation on Portrait and Margins on Small, so every page sits the same way with a little white space around it. Leave One PDF per image off: the point is a single document. Press Convert to PDF.
On the result screen, Compress PDF is among the suggestions under Send to another tool. Pick it, and once more, don't download.
Step 4: Make it small enough to send, then download it
Nine pages of photographed paper make a heavy PDF, more than you want to push through an email to someone you haven't met yet.
In Compress PDF, choose Recommended, which the tool describes as balanced for email, sharing and archiving. Screen is smaller still, but it can soften faint pencil marks. Press Compress PDF. The result screen shows the old and new sizes side by side.
Now comes the one break from the pattern. Download this file. It is the copy you will email to the manufacturer and the copy you will keep, and the next step only produces a small proof file, not a PDF. Save it somewhere you will not touch it, give it a clear name like bike-rack-notebook-2026-10.pdf, and don't open it in an editor afterwards.
Then, still on the same result screen, open Other compatible tools and choose Timestamp File. The handoff sends the exact bytes you just downloaded.
Step 5: Stamp it
Timestamp File starts on its own as soon as the PDF arrives. It calculates the file's SHA-256 fingerprint in your browser and sends only that 64-character string to the OpenTimestamps calendar servers. The drawings themselves never leave your computer.
A few seconds later you get a small .ots file named after your PDF. Download it and save it in the same folder as the PDF. The two belong together: the PDF on its own proves nothing, and the .ots on its own is meaningless.
The proof starts out pending. It becomes fully confirmed once the batch it belongs to lands in a Bitcoin block, which can take from minutes to a few hours. You don't need to wait before sending your email.
Why this order
Stamp last, because the proof covers exact bytes. A timestamp vouches for one file, byte for byte. Rotate a page, compress again, or even open the PDF and save it, and the fingerprint changes completely. A verifier then reports a mismatch, not a later date. So the stamp has to be the final thing that happens to the file.
Compress before stamping, not after. It is tempting to stamp the full-quality PDF and send a compressed copy. But the file the manufacturer receives is the one that matters if anyone ever disputes the date, and a compressed copy is a different file with a different fingerprint. Stamp what you send, and send what you stamped.
Keep the download from step 4, because you can't remake it. The compressor writes the current date and time into the PDF it creates. Run the same photos through the same five steps tomorrow and you get a PDF that looks identical but doesn't match your proof. The file you downloaded in step 4 is the only one that ever will.
Fix the pictures while they are still pictures. Rotation and ordering happen before the PDF exists because a PDF made from sideways photos has sideways pages baked in. Converting from HEIC comes first only because nothing downstream reads it.
One honest limit: the timestamp proves these exact pages existed no later than a given date. It doesn't prove you drew them, and it is not a patent or a contract. What it does is turn "I had this in March" from your word into a date anyone can check.
What you end up with
Two files in one folder: a single PDF of your notebook, in the right order with every page upright, small enough to email, and a .ots proof that ties that exact PDF to a Bitcoin block. You send the PDF to the manufacturer and keep both files untouched. If the date ever matters, the PDF and its proof go into a verifier together and come back with the block date. The whole chain takes a few minutes and one download for each of the two files.
Ready to start? Open Image to JPG →