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Gerber and Excellon file inspector

coordinate = digits × 10⁻ᵈ, where d is the decimal count declared by %FS (Gerber)

Drop a Gerber RS-274X layer or an Excellon drill file: the tool reads it entirely inside your browser and reports the recognised format, the units the file itself declares, the extents and dimensions of the copper or drilled material, then the per-type count of primitives. The parser is strict: any command outside the recognised subset, any truncated data and any ambiguous coordinate produce a refusal located by line number and byte offset. Never a partial result presented as valid. The file is never uploaded, never converted. Never stored.

Drag a file here or

No form to fill in: drop the file and the verdict appears at once. Common extensions: .gbr, .ger, .gtl, .gbl, .drl, .xln, .txt.

Analysed file: No file dropped yet.

File processed locally, never uploaded. The shareable link never contains the dropped file: it has to be dropped again to replay the analysis.

Applied limits

These limits protect the browser. They are enforced by the parser: a file exceeding them is refused, never silently truncated.

  • 2,097,152 bytes per file
  • 200,000 lines
  • 200,000 commands
  • 1,000 apertures or tools

Recognised formats

Gerber RS-274X and Excellon (drilling), read strictly: any command outside the recognised subset is refused with its line and byte offset, never ignored.

Scientific dossier

What the tool computes, what it assumes, where it stops being valid, and where its data comes from.

Method & formulascoordinate = digits × 10⁻ᵈ, where d is the decimal count declared by %FS (Gerber)

coordinate = digits × 10⁻ᵈ, where d is the decimal count declared by %FS (Gerber)

extents = union of (point ± half the aperture extent or half the tool diameter)

width = maxX − minX ; height = maxY − minY

length in millimetres = length in inches × 25.4

An inspector models nothing: it reads what the file declares and derives a single quantity from it, the extents. Those extents describe the material, not the coordinates. Every point is widened by the radius of the Gerber aperture or the Excellon tool that draws it, because a 0.5 mm trace centred on the board edge overhangs it by 0.25 mm. Arcs are bounded by the cardinal points they actually sweep, not by their endpoints alone: using endpoints only would underestimate the extents of every arc crossing an axis.

Gerber RS-274X
· text format describing one layer of a printed circuit board through apertures (shapes) and operations (draw, move, flash). The file carries no version number, so none is reported for a Gerber file.
Excellon
· text format describing a drilling program: a header defines the tools and their diameters, the body lists the drilled positions. The fmat line, when present, is the only version the file declares.
%FS (format specification)
· Gerber command that declares numerically where the decimal point sits in coordinates (for instance 3.6: three integer digits, six decimals). It is what makes implicit-decimal coordinates unambiguous.
Aperture
· shape used to draw or flash: circle C, rectangle R, obround O, regular polygon P. Its extent is part of the computed extents.
Zero suppression (LZ / TZ)
· Excellon keyword meant to state which zeros are omitted in coordinates without a decimal point. CAM toolchains use it in both opposite senses: this tool records it, displays it, and refuses to derive a value from it.
Validity domainThe parser is deliberately strict: an accepted file has been understood command by command, with no line skipped.

The parser is deliberately strict: an accepted file has been understood command by command, with no line skipped. Refused. At their line and byte offset: aperture macros %AM (their geometry cannot be bounded without interpreting it), step and repeat %SR, single-quadrant G74, deprecated Gerber commands (%MI, %OF, %SF, %IN, %LN, %IP, G54, G70/G71, G90/G91, M00/M01), Excellon routing (G00 to G03, M15 to M17) and incremental mode. Excellon coordinates without a decimal point are refused as well: reading them depends on the LZ/TZ keyword, which is used in both opposite senses across software, and no verifiable primary source settles it for all of them. Inventing a factor of 10ⁿ on a board dimension would be exactly the silent error an inspector must make impossible (ADR-0012, ADR-0028). Re-export the file with explicit decimals instead.

Privacy and protection limitsFile processed locally, never uploaded: reading and analysis happen entirely inside your browser, no byte is sent to a server, nothing is kept once the tab is closed, and the dropped file never enters the shareable link.

File processed locally, never uploaded: reading and analysis happen entirely inside your browser, no byte is sent to a server, nothing is kept once the tab is closed, and the dropped file never enters the shareable link. To protect the browser, the parser applies and displays four limits: 2 MiB per file, 200,000 lines, 200,000 commands, 1,000 apertures or tools. A file that exceeds them is refused before being read, together with the limit reached; it is never silently truncated.