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Chapter 20 · Sources & methodology
A reference is only as good as its evidence trail. This chapter explains how the Photopea reference was researched, what tiers of evidence were used, which sources disagreed and how those disagreements were resolved, and how you can get a correction made. It is deliberately unglamorous, because the point of an editorial policy is to be checkable rather than persuasive.
How this reference was built
The research followed four passes. The first pass read Photopea's own documentation end to end, because the developer's documentation is unusually detailed and is the primary source for almost every behavioural claim. The second pass exercised the application itself against a fixed set of test files — a layered PSD, a CMYK TIFF, a RAW file, a Sketch file, a Figma export, an INDD package — and recorded what actually happened rather than what the documentation said would happen. The third pass read the public issue tracker and forum, which is where the developer answers questions that the documentation does not cover, including the gaps and the deliberate omissions. The fourth pass cross-checked every claim that mattered against at least one independent source: a review, a tutorial, or a second-hand account from a practitioner.
Where the documentation and the observed behaviour disagreed, the observed behaviour was recorded and the discrepancy was noted in the chapter. Where the developer stated a position in an issue thread, that statement was treated as authoritative over third-party reviews. Where two third-party sources disagreed and neither was primary, the disagreement is described rather than resolved by preference.
Evidence tiers
| Tier | What it means | How it was used |
|---|---|---|
| Primary — documentation | Photopea's own documentation, API reference and release notes | Default source for feature behaviour, formats and limits |
| Primary — direct testing | Observed behaviour in the application against fixed test files | Used to confirm documentation and to record undocumented behaviour |
| Primary — developer statements | Replies from the developer in the issue tracker and forum | Used for gaps, roadmap positions and design decisions |
| Secondary — independent review | Published reviews, tutorials and practitioner write-ups | Used to cross-check and to surface usability issues |
| Tertiary — reference works | Encyclopaedic entries and aggregator pages | Used only for dates, version history and company background, never for feature claims |
Primary sources
- Photopea — main application and feature documentation, photopea.com/learn/ (accessed November 2026). The canonical description of tools, panels, formats and behaviour.
- Photopea — API and scripting reference, photopea.com/api/ (accessed November 2026). Source for the scripting objects, the plugin iframe protocol and the postMessage interface described in chapter 10.
- Photopea — pricing and plans page, photopea.com/pricing (accessed November 2026). Source for the plan structure, prices and the credit system described in chapters 9 and 11.
- Photopea — privacy documentation, linked from the application footer (accessed November 2026). Source for local processing, the six-month inactivity deletion policy and the
_ppppreferences cookie. - Photopea — in-application keyboard shortcut list, Help > Keyboard Shortcuts (accessed November 2026). Source for chapter 12.
- Photopea — public issue tracker and forum, photopea.com/forum and the associated GitHub issue threads (accessed November 2026). Source for developer statements on missing features, including the offline question (issue #6760) and the AI opt-out question (issue #8291).
- Photopea — release notes and version announcements for versions 4.0 through 5.6 (accessed November 2026). Source for the version history table in chapter 11.
- Photopea — terms of service and commercial licensing terms (accessed November 2026). Source for the distinction between personal and commercial use described in chapter 11.
Independent and secondary sources
- Wikipedia — Photopea entry (accessed November 2026). Used for company background, launch date and the self-hosting cost range referenced in chapter 11. Not used for feature claims.
- Independent progressive web app analysis of photopea.com (accessed November 2026). Source for the finding that no active service worker cache was present, which informs the offline discussion in chapters 10 and 11.
- Published reviews and comparison articles covering Photopea against Photoshop, GIMP and Affinity Photo (accessed November 2026). Used to cross-check the competitive positioning in chapter 19 and to surface usability issues that documentation does not mention.
- Practitioner tutorials and forum discussions on PSD round-tripping, smart object behaviour and text rendering fidelity (accessed November 2026). Used to confirm the PSD fidelity claims in chapters 2 and 3.
- Adobe documentation for Photoshop, used as the reference standard for feature parity claims (accessed November 2026). Where this reference says a feature matches Photoshop, the comparison is against Adobe's documented behaviour.
- GIMP, Affinity Photo and Figma documentation, used for the comparative claims in chapter 19 (accessed November 2026).
Where sources disagreed
Two disagreements were material enough to document rather than smooth over.
The first is self-hosting. Photopea's own materials and most reviews state that the application cannot be self-hosted. The Wikipedia entry and some distributor materials reference self-hosting arrangements costing between five hundred and two thousand US dollars per month. Both cannot be literally true. The resolution adopted here is that self-hosting exists as a commercial distributor arrangement rather than as a downloadable product, which reconciles the two claims without pretending one is simply wrong. Chapter 11 states this explicitly and flags it as an inference rather than a documented fact.
The second is offline capability. Photopea's documentation states that the application can be used offline after loading. Independent analysis found no active service worker, which would mean a cold start requires a network. These are not contradictory once the distinction between "editing offline within a session" and "launching offline" is made, and chapters 10 and 11 make that distinction rather than choosing one source over the other.
A third, smaller disagreement concerns whether Photopea's Camera Raw filter constitutes a real raw development pipeline. Reviews differ. The position taken here is that it is a partial implementation, useful for exposure and white balance but not a substitute for a dedicated raw developer, and chapter 6 states the specific gaps.
What this reference does not claim
It does not claim to be exhaustive at the level of every menu item. Photopea ships continuously, and a list of every dialog would be stale within weeks. The reference aims to be complete at the level of capability: what the tool can and cannot do, where the boundaries are, and which boundaries matter for which kind of work.
It does not claim independence from the underlying documentation. Where a claim rests on Photopea's own documentation, that is the source, and the documentation could be wrong. Direct testing was used to reduce that risk, but testing was not exhaustive and was performed on a fixed set of files on a fixed set of browsers.
It does not claim to be a tutorial. There are many good Photopea tutorials and this is not one of them. The purpose here is decision support: helping you know whether the tool fits the job, and where its edges are.
Corrections
If you find something in this reference that is wrong, out of date, or unfair to the product, write to contact@photoedit.in with the chapter and the specific claim. Corrections that are verifiable are applied and the "updated" date on the affected chapter is changed. Where a correction changes a conclusion rather than a detail, the change is described in the chapter rather than made silently.
This reference is reviewed on a rolling basis, with a full pass whenever Photopea ships a version that changes capability. The current review date is 4 November 2026. The editorial standards behind this process are set out in the editorial policy.
How to cite this reference
If you are citing this work, cite the specific chapter rather than the hub, because chapters are updated independently. A suitable citation is: photoedit.in editorial team, "Photopea reference: [chapter title]", photoedit.in, updated 4 November 2026, https://www.photoedit.in/photopea/[slug]/. Each chapter carries a canonical URL and machine-readable TechArticle metadata for exactly this purpose.
Return to the reference overview for the chapter index and the five-minute verdict.