TL;DR
Thorsten Meyer says an AI coding agent produced a working first version of his private PDF editor, Docestra, on Nov. 6, 2026. Tests on real files revealed problems with saving, encrypted documents and redaction; by Nov. 12, version 1.5.1 had 745 unit tests and 32 browser test suites, according to his project records. The app is private, and its developer has not measured time or cost savings.
Thorsten Meyer says testing real documents led him to revise Docestra, a private PDF editor built with AI coding agents, during six days of development from Nov. 6 to Nov. 12, 2026. The tests exposed a save bug and limitations with encrypted PDFs, while an independent AI review identified problems in an early redaction design, according to his project records.
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Meyer says he gave an AI coding agent a one-sentence brief on Nov. 6 to build a PDF editor for his own use. The first working version was committed that evening at 21:47 Central European Time. It could open PDFs, add annotations and signatures, fill forms, rearrange pages and save files. He describes the app as a local TypeScript web app that runs in a browser on his Mac, with files staying on the machine. The code was written by AI agents running Claude Opus, with OpenAI’s Codex reviewing it from the start, he says.
A test run over 930 real PDFs found that saving could produce a broken cross-reference table in a file made by a common PDF generator, causing markups to disappear from the saved document. Meyer says he changed the save process to avoid compressed object streams. Tests also found that 52 of 69 encrypted PDFs restricted annotations. Because the PDF library could not re-encrypt files after editing, Docestra was changed to ask for confirmation before unlocking a file and to save an unprotected copy, leaving the original untouched. Meyer says all 69 encrypted test files then unlocked.
Redaction prompted a separate redesign. The first version’s “white-out” feature covered text without removing it, a limitation the development plan disclosed. On Nov. 8, Meyer built a redaction feature intended to remove content. An independent AI review found 14 problems in its first review round and 13 in the second, according to his account. He says he then abandoned that design for a simpler one; tests across 917 PDFs found zero leaks. The project log dates version 1.5.1 to Nov. 12 and lists 745 unit tests and 32 browser test suites.
What Reliability Required
The development account illustrates the gap between a tool that works in a demonstration and one that can handle varied documents. A save defect may not be visible until a user reopens a file, while a visual cover-up can leave sensitive text embedded in the PDF. Those are practical risks for people who annotate or redact contracts and other records.
Meyer’s account also describes decisions that involved more than adding features: preserve originals, disclose encryption limits, and replace a redaction approach after repeated review findings. The test totals and results are reported by the developer; they do not establish how Docestra performs across every PDF or in other users’ workflows.
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Six Days of Revisions
Docestra began as a personal project on Nov. 6, 2026. Its first version included document viewing and search, highlights, drawings, notes, shapes, signatures, form filling, page rotation and reordering, combining and extracting pages, printing, undo and saving. Meyer says the initial version handled the files he had tried, but a broader robustness run on the first day exposed the save issue.
The project’s timeline records encryption changes on Nov. 7 and the redaction redesign on Nov. 8. Version 1.5.1 followed on Nov. 12. Meyer says development of version 2.0 began Nov. 13, with a plan to create one shared PDF engine for AI agents. That version was still in development when he published the account. Docestra remains private and is not available to download.
“Vibe coding gets you a working tool quickly. Turning it into a tool you can rely on is the real work.”
— Thorsten Meyer, describing the project’s development
What the Tests Establish
The reported results come from Meyer’s project records and testing; the account does not provide an external audit of the test methods or results. It also does not identify the full range of PDF generators, readers or document types represented in the 930-file run, or describe the 917-file redaction checks in enough detail to assess their coverage.
Meyer says he has not measured time or cost savings. Docestra is private, so other users cannot independently try the current version based on this account. Version 2.0’s shared engine is a development plan, not a finished feature.
Version 2.0 Remains in Development
Meyer says work on Docestra 2.0 started on Nov. 13, 2026, with the aim of building one PDF engine shared by the project’s AI agents. He did not provide a release date, and the version was unfinished at the time of writing. The next documented milestone is completion of that development, but the account gives no schedule or public release plan.
Key Questions
What is Docestra?
It is a private PDF editor that Thorsten Meyer says he built for his own use with AI coding agents. It runs locally on his Mac in a browser and is not available to download.
What did testing find?
Meyer says a run over 930 real PDFs exposed a save bug that could make markups disappear. Tests also found that 52 of 69 encrypted files did not allow annotations under their authors’ restrictions.
Did the first redaction feature remove text?
No. Meyer says the first version’s white-out feature covered content while leaving the text underneath in the PDF. He later built a redaction feature, changed its design after two rounds of independent AI review, and reports zero leaks in tests across 917 PDFs.
Is Docestra 2.0 available?
No. Meyer says development began on Nov. 13, 2026, and the version was still unfinished. He has not given a release date.
Source: Thorsten Meyer AI
