How to open a SchDoc file without Altium.
A .SchDoc is Altium's proprietary schematic document — not a file you can open by renaming it or with a generic “opener,” and not something you need an Altium licence to read. This guide covers the honest ways to open one without Altium — free, in your browser or in an EDA tool — and the one thing to know before you treat what opens as a working copy of your design.
The free SchDoc viewer is live — open your file in the browser. This guide covers the other honest options too.
You can't open a .SchDoc by renaming it — but you don't need Altium either.
A .SchDoc is a binary Altium schematic file (SchDoc = schematic document — the schematic-sheet counterpart to a .PcbDoc board). The pages that tell you to rename it to .txt or install a generic “.SchDoc opener” are wrong: the format is proprietary, and only an EDA tool that understands it can read the schematic. The good news is you don't need an Altium seat to do that. Free, cross-platform tools open a .SchDoc — and one of them, KiCad, can also bring it into your own workflow. Which one you want depends on why you're opening the file: to take a look, to keep working, or to move it into KiCad and check what came across.
Renaming a .SchDoc doesn't open it. An EDA-native reader does.
How to open a .SchDoc without Altium — pick by what you're doing.
Every one of these is free and needs no Altium licence. They differ in what you get: a quick render, a copy you can keep working in, or an official view. Where a caveat is a documented KiCad behavior, it links to KiCad's own docs or public tracker.
- 01
Open it in your browser (a free schematic viewer)
For a quick look — no install.The fastest way to see what's on the sheet is a browser-based viewer that parses the .SchDoc and renders it. Note a real gap here: the popular free viewers render the PCB (the .PcbDoc board) — a .SchDoc schematic has been the under-served corner, so check a viewer actually opens schematics, not just boards. Crosspad's free SchDoc viewer covers exactly this corner: it opens the schematic in the browser, on any OS, and nothing is uploaded. Its migration-readiness inspector lands at launch.
Open a .SchDoc in the free viewerMost browser viewers are view-only — you can look, not edit or export. And a viewer is a render, not a verdict: whether a design migrates to KiCad cleanly is answered by the migration analysis, not by anything drawn in a browser tab.
- 02
Open it in KiCad (free, and yours to keep)
For actually working with the design.KiCad is free, open-source and cross-platform (Windows, macOS and Linux), and it imports Altium schematics natively — so it doesn't just show you the .SchDoc, it brings the design into a tool you own. To open one: install KiCad, then use File → Import → Non-KiCad Project / Altium, and point it at your .SchDoc (or the whole .PrjPcb project). The symbols come across and the sheet opens.
Convert & verify a .SchDocOpening a .SchDoc in KiCad is a migration, not a view — and a standard migration can quietly change the connectivity underneath a sheet that looks right. Net assignment and label case have documented edge cases in how Altium nets come across; on KiCad ≤10.0.4 shared-member buses could arrive unconnected (fixed in 10.0.5); channel designators can be stripped so distinct parts collide. So KiCad is the right path if you want the design in your own tool — just treat the result as something to verify, not trust on sight.
- 03
Altium's own free web viewer
For an official render without buying a seat.Altium publishes a free browser-based viewer (Altium 365) that opens .SchDoc and .PcbDoc files. It's the official render, so fidelity to the source is not in question.
It's view-only, and it means uploading your design to Altium's cloud and signing in — fine for a look, not a path to owning or migrating the design.
On a Mac or Linux — or moving off Altium for good?
Altium has no macOS or Linux build, so if that's why you can't open the file, you're probably not just looking — you're a migration waiting to happen, and KiCad is already the tool most people in that spot land on. Opening the .SchDoc is step one. The real question is whether the design comes across intact. A schematic opened in KiCad looks clean, but the netlist underneath — net assignment, buses, harnesses, channel designators — is exactly where a standard migration can silently differ, each documented in KiCad's own docs and public tracker. That's the difference between a file that opens and a design you can build from. Before you commit, it's worth knowing which side of that line your file is on.
Frequently asked questions.
How do I open a .SchDoc file without Altium?
You have three free options and none needs an Altium licence: open it in a browser-based schematic viewer for a quick look; import it into KiCad (free and cross-platform) to keep working in it; or use Altium's own free web viewer for an official render. What doesn't work is renaming the file or a generic “file opener” — a .SchDoc is a proprietary binary schematic that only an EDA tool can read.
What is a .SchDoc file?
It's Altium Designer's schematic document format (SchDoc = schematic document) — the schematic-sheet counterpart to a .PcbDoc board file. It's binary and proprietary, so it can only be read by software that understands the Altium format, not by a text editor or a generic viewer.
Can I open a .SchDoc in KiCad?
Yes — KiCad imports Altium .SchDoc schematics natively (since version 7): File → Import → Altium, and point it at the file. The symbols and the sheet come across. Keep in mind that importing is a migration, not just a view: connectivity can change silently — shared-member buses could arrive unconnected on KiCad ≤10.0.4 (#20707, fixed in 10.0.5), channel designators can be stripped so distinct parts collide (#24861) — so verify the netlist rather than trust the render.
Is there a free online SchDoc viewer?
Yes — a browser viewer can open a .SchDoc without any install. Worth knowing: several popular free Altium viewers render the PCB board only and skip the schematic, so check the viewer actually opens .SchDoc schematics. Crosspad's free SchDoc viewer covers that gap: it renders the schematic in the browser, on any OS, with nothing uploaded. A viewer renders the sheet; it does not judge whether the design migrates cleanly — that answer comes from the migration analysis, and Crosspad's readiness inspector lands at launch.
Do I need to convert my .SchDoc to KiCad to open it?
No — opening and converting are different things. To just read the schematic, a viewer is enough and nothing changes. To keep working in the design outside Altium, import it into KiCad and verify the connectivity came across. Choose by what you actually need to do with the file.
Can I open a .SchDoc by renaming it to .txt or .pdf?
No. It's a binary format — renaming it doesn't convert it and reveals nothing readable. Use an EDA-native reader (KiCad, a schematic viewer, or Altium's web viewer) instead.
Open your .SchDoc, then see if it's ready for KiCad.
Take a look at the schematic without Altium — and when you're deciding whether to move it to KiCad, get evidence of what the migration keeps, what it repairs, and what it flags for you.
Version-specific behavior reflects a standard Altium → KiCad schematic migration as of KiCad 10.0.6 (2026-08-29). It changes most releases — the shared-member bus issue (#20707), for example, was fixed in 10.0.5 and is scoped ≤10.0.4. This guide is refreshed per release.