If vendor lock-in is the disease, open formats are the vaccine. An open format is a file format anyone can read and write without permission — published, documented, implemented by many tools. When your data lives in open formats, no single company’s decisions can strand it. The app can shut down, the company can pivot, the CEO can retire to a sailboat; your files remain readable, convertible, and yours.
This guide is your field manual for open formats: which standards matter for which data, how to verify an app’s claims, and how to build a workflow where openness is the default. It is the constructive companion to our lock-in analysis in How to Audit Your Subscriptions in Under an Hour thinking and connects to the data-deletion realities in What Happens to Your Data When an App Shuts Down.
What “open” actually means
“Open” gets thrown around loosely, so here is the working definition: a format is open if its specification is publicly documented, royalty-free to implement, and supported by multiple independent tools. Plain text, CSV, JSON, JPEG, PNG, PDF, Markdown — all open by this standard. A format owned by one company, documented partially or not at all, readable only by their software — that is proprietary, whatever the marketing says.
There is a useful middle category: formats controlled by one company but openly documented and widely implemented. These are “open enough” for practical purposes — your data is safe as long as the documentation and the independent implementations exist. The risk spectrum runs from fully open standards (safest) through documented-but-controlled formats (fine in practice) to undocumented proprietary formats (avoid for important data).
Openness is not only about files. Open protocols (how apps talk to each other), open APIs (how you programmatically access your data), and open-source applications (where the code itself is inspectable) all reduce lock-in through the same mechanism: removing the single company’s exclusive control. Files are the foundation; the rest is reinforcement. When evaluating an app, check all four layers — format, protocol, API, and code — and weight them by what you need: for most people, open formats plus a decent API cover nearly every realistic exit scenario.
The formats that matter, by data type
Text and notes: Markdown and plain text
For anything you write, Markdown is the sweet spot — human-readable as plain text, with just enough structure (headings, lists, links, emphasis) to preserve meaning. Every serious notes app reads and writes it. Plain .txt is the even simpler fallback that will outlive us all. If your notes app exports to either, your words are safe.
Structured data: CSV and JSON
Contacts, transactions, tasks, logs — CSV for flat tables, JSON for nested structures. Both are universal, both are human-inspectable, and both import into virtually everything. When an app exports your structured data as either of these, the data has a future independent of the app.
Documents: PDF/A and office-open formats
For documents of record, PDF/A — the archival variant of PDF — is the preservation standard, designed specifically for long-term readability. For editable documents, the open office formats (ODT, ODS) are the standards-based choice, though in practice the common commercial formats are so widely supported they function as de-facto standards. Keep both the editable original and a PDF/A archival copy for anything important.
Photos, audio, video: the settled standards
JPEG and PNG for images, MP3/FLAC for audio, MP4 for video — these battles were settled years ago and the winners are deeply entrenched. The main thing to check is that you get originals, not re-encoded derivatives, and that metadata (dates, locations) survives the export.
How to verify an app’s openness claims
Marketing loves the word “open.” Verify it with three tests. The round-trip test: export your data, then import it into a competing app — if your content arrives intact, the format is genuinely interoperable. The stranger test: hand the exported file to someone without the app — can they open it with free tools? The decade test: could someone in ten years, with no knowledge of this app, make sense of the file? Formats that pass all three are the real thing.
Read the export documentation skeptically. “Export to PDF” for a database app is openness theater — you get a picture of your data, not your data. “Full export” that omits attachments, history, or metadata is partial openness wearing a complete costume. The tests above cut through the language; run them before you commit important data.
Building an all-open workflow
The strongest position is a workflow where every link in the chain uses open formats by default. Notes in Markdown, synced as files you can see. Tasks in an app with CSV export. Files in standard formats in a folder structure you control. Photos as JPEGs with metadata intact. Each choice is small; together they mean no single shutdown can strand you, because your data was never captive in the first place.
You do not have to rebuild everything at once. Migrate opportunistically: when you adopt a new app, choose the open option; when an old app frustrates you, replace it with an open one; when you export, prefer open formats and convert the rest. Over a year or two, the workflow converges on openness without a disruptive overhaul. Our dependency-audit thinking helps prioritize which links to convert first.
The sync layer: files you can see
One underappreciated openness choice: prefer apps that store your data as visible files in a folder over apps with opaque internal databases. Visible files can be backed up by any backup tool, opened by any compatible app, and inspected directly. Opaque databases require the app’s cooperation for everything. When the app is the only key to your data, you have lock-in regardless of the format inside.
The honest limits of open formats
Open formats are necessary but not sufficient. They preserve your data, not your workflows — the automations, integrations, and muscle memory do not export. They do not help with social lock-in — your collaborators are still wherever they are. And some data genuinely has no good open representation: complex relational structures, app-specific interactive features, real-time collaboration state.
None of this diminishes their value; it just scopes it correctly. Open formats solve the data-captivity problem completely and the other problems not at much. That is still the highest-leverage single choice in this entire guide — it just is not the whole strategy. Pair it with the export cadences, the dependency audits, and the exit plans, and you have the complete system.
Voting with your data: why your format choices matter beyond you
Every time you choose the app with the open export over the one with the prettier lock-in, you cast a small economic vote. Companies track why users choose competitors, and “better data portability” shows up in those analyses more than you might expect. Your individual choice will not change an industry; a million such choices visibly move markets toward openness.
You can amplify the effect by saying why. When you leave an app, tell them — briefly, specifically — that export quality factored into the decision. When you choose an app, mention in a review that the open formats mattered. Product managers read this feedback; it is among the cheapest market research they get, and it directly informs roadmaps. The quiet majority that cares about portability only matters if it speaks.
Support the institutions too: the standards bodies that maintain the formats, the open-source projects that implement them, the regulators pushing portability rules. Openness is infrastructure, and infrastructure needs maintenance. A donation, a bug report, a thank-you email — small contributions to the commons that your entire data strategy rests on.
Frequently asked questions
What is the quickest openness check for a new app?
Sign up, add test data with an attachment, export everything, and try opening the result with free tools you already have. Five minutes, one verdict: if the export opens cleanly elsewhere, the app passes. Make this your standard signup ritual for anything holding important data.
Can’t I just convert proprietary formats later if needed?
Sometimes, unreliably, under time pressure — which is exactly when conversion fails. Community converters exist for popular apps but break with updates, handle edge cases poorly, and may not exist for the app you chose. “Convert later” is a hope, not a plan. Prefer native open formats now.
Is HEIC open enough for photos?
HEIC is a legitimate modern standard with broad device support, though less universal than JPEG. For archival purposes, keep JPEG copies alongside HEIC originals — compatibility today, quality preserved for tomorrow. The belt-and-suspenders approach costs little and covers both futures.
Do I need open-source apps, or are open formats enough?
Open formats are enough for data safety; open source adds insurance for the software itself. If your priority is “my data survives any shutdown,” formats are the requirement and open source is a bonus. If your priority extends to “the tool itself survives,” open source matters more. Match the solution to the concern.
What if my employer mandates a closed app?
Then openness is not your call — but personal exports still are, where policy allows. Keep your own copies of your work product in open formats alongside the mandated system, within the bounds of company policy. You cannot fix the company’s lock-in, but you can keep your own portfolio portable.
Open formats are the closest thing this industry has to a guarantee: not that apps will survive, but that their deaths will not take your data with them. Learn the standards, run the three tests, and build toward the all-open workflow one choice at a time. The companies will do what companies do. Your files will remain yours.