Free Online Gerber Viewer &
PCB Layer Inspector
High-speed, privacy-first RS-274X Gerber and Excellon drill file inspection directly in your browser. Inspect copper traces, check clearances, verify annular rings, and perform emergency trace patches without sending a single byte of your PCB design to external servers.
Drag & Drop Gerber files or ZIP archive here
Processed 100% locally on your machine with zero server transmission.
Supports standard extensions: .GTL, .GBL, .GTS, .GBS, .GTO, .GBO, .DRL, .GKO, .TXT, .GBR, and .ZIP
100% Private, Client-Side Engine
Why hardware engineering teams and PCB designers choose GerberPatch over conventional cloud viewers for sensitive prototypes and proprietary schematics.
How Our In-Browser Engine Operates
Traditional online Gerber viewers rely on server-side rendering, requiring you to upload proprietary RS-274X layout files to external servers. This introduces intellectual property exposure, violates corporate non-disclosure agreements (NDAs), and leaves your designs vulnerable to data breaches.
GerberPatch revolutionizes this workflow. Our proprietary parser compiles vector geometries, flashes apertures, and computes boolean layer intersections directly on your computer's CPU using modern Web APIs. No Gerber data, board coordinates, or file metadata is ever transmitted across the network.
- • Zero cloud file transmission or remote database storage
- • Works completely offline once loaded in your browser
- • Enterprise NDA compliant for commercial & defense hardware
Zero-Data-Loss Offline Auto-Recovery
Ever accidentally closed your browser tab in the middle of inspecting an intricate 6-layer board? GerberPatch incorporates an offline IndexedDB session auto-save engine.
Your active layer visibilities, custom color assignments, patch histories, and coordinate viewports are continuously preserved in your browser's local sandboxed storage. If your browser closes, reopen GerberPatch to seamlessly restore your exact workspace in one click—with zero external synchronization.
All locally stored sessions can be permanently wiped with one click using the "New Project (Clear Session)" function, immediately returning your local storage to a zero-footprint state.
High-Precision PCB Inspection & Patch Capabilities
Everything you need to review CAD exports, verify copper clearances, measure pad pitches, and make emergency corrections before manufacturing.
1nm Precision Math Engine
Floating-point arithmetic in JavaScript can accumulate tiny rounding errors during coordinate transformations. GerberPatch scales all coordinates into 1nm integers before performing geometry calculations, guaranteeing 0% coordinate drift.
EDA Industry Theme Presets
Switch instantly between curated color schemes including JLCPCB Green, Dark Knight, Classic CAD Blue, and High-Contrast Monokai. Toggle between Black, Slate, and Light canvas backgrounds to optimize visual inspection.
Magnetic CAD Snapping & HUD
Snap precisely to pad centers, trace vertices, and drill hole coordinates with intelligent magnetic CAD snapping. A real-time Heads-Up Display (HUD) shows absolute coordinates and relative delta offsets (ΔX, ΔY).
Visual Differential Mode
Toggle visual diff mode to immediately illuminate injected patches, modified solder mask clearances, and severed traces in high-visibility cyan against original board routing.
Semantic Subsequence Verification
Exported Gerber files are verified by our automated semantic subsequence validator, confirming that 100% of original physical apertures and untouched vector commands remain completely uncorrupted.
Emergency Patching & Export
Fix routing errors without re-running full CAD DRC pipelines. Cut shorted tracks with precision erasers, inject new signal traces, add text annotations, and export ready-to-order RS-274X files and ZIP packages.
Comprehensive Gerber File Extension Reference
Standard Gerber RS-274X and Excellon NC Drill file extensions, layer mappings, and critical pre-manufacturing inspection checkpoints.
| Extension | Layer Function | Description & Purpose | Default Color | Critical Inspection Checklist |
|---|---|---|---|---|
| .GTL | Top Copper Layer | Primary component pads (SMD), high-speed trace routing, power rails, microvias. | Red / Copper | Check trace necking, minimum clearance (≥5mil), and solder mask expansion. |
| .GBL | Bottom Copper Layer | Bottom ground planes, power return paths, through-hole solder pads, connector fanouts. | Blue / Cyan | Verify ground plane continuity, copper pour clearances from board edge, high-current width. |
| .GTS | Top Solder Mask | Top solder resist negative mask. Exposes copper pads to prevent solder bridging during reflow. | Purple / Green | Ensure solder mask dam width (≥0.1mm) between adjacent IC pins to prevent shorts. |
| .GBS | Bottom Solder Mask | Bottom solder resist openings for THT leads, wave soldering pads, and bottom SMD components. | Green / Teal | Check through-hole solder clearance and verify test points are properly uncovered. |
| .GTO | Top Silkscreen / Overlay | Component reference designators (R1, C1, U1), polarity marks (diode bars, pin 1 dots), logos. | Yellow / White | Verify no silkscreen ink overlaps bare copper SMD pads (causes soldering defects). |
| .GBO | Bottom Silkscreen / Overlay | Bottom component markings, certification labels (CE, FCC), revision numbers, barcodes. | White | Ensure text height (≥1.0mm) and stroke width (≥0.15mm) meet manufacturer legibility limits. |
| .DRL / .TXT | Excellon NC Drill File | Plated Through Holes (PTH), Non-Plated Holes (NPTH), via holes, mounting slots. | Orange / White | Verify annular ring breakout tolerance (pad diameter ≥ drill size + 0.3mm). |
| .GKO / .GML | Keep-Out / Board Outline | Physical PCB board contour, internal slot cutouts, V-scoring grooves, milling coordinates. | Pink / Magenta | Ensure copper pour keep-out distance (≥0.3mm from edge) to avoid shorting during routing. |
Pre-Flight PCB Inspection & DFM Checklist
Follow this essential 3-step Design for Manufacturing (DFM) verification guide before submitting your Gerber archive to PCB manufacturers (e.g. JLCPCB, PCBWay, Oshpark, Eurocircuits).
Trace Clearance & Width Check
Verify that your minimum copper trace width and spacing adhere to your fabricator's process capabilities (standard is typically 5mil/5mil or 0.127mm).
- Inspect high-current traces for adequate width to prevent overheating.
- Ensure copper pour keepout is at least 0.3mm away from board outlines.
- Check for acute trace angles (<90°) that trap acid etchant.
Drill Registration & Annular Ring
Overlay your Excellon NC Drill file (.DRL) on top of copper layers (.GTL/.GBL) to confirm precise alignment and hole sizing.
- Verify annular ring margin (pad radius minus drill radius ≥ 0.15mm).
- Prevent drill breakout during CNC drilling misalignments.
- Confirm Plated (PTH) and Non-Plated (NPTH) hole separation.
Solder Mask Dam & Bridge Prevention
Examine solder resist openings (.GTS/.GBS) around fine-pitch ICs (QFN, QFP, BGA) to prevent solder bridging during reflow assembly.
- Ensure green solder mask dam width between SMD pads is ≥ 0.1mm.
- Verify that all test points and fiducial marks have mask openings.
- Confirm no silkscreen legend ink is printed directly on exposed solder pads.
Got Questions? We Have Answers.
Everything you need to know about viewing, measuring, and editing Gerber files online.
What is an Online Gerber Viewer and how does it work?
Is it safe to view confidential or proprietary PCB Gerber files here?
Which Gerber formats, drill files, and PCB design CAD tools are supported?
Can I measure trace spacing, pad dimensions, and board sizes?
Can I modify, cut traces, or add annotations to Gerber files online?
Is GerberPatch completely free, and does it require an account?
Ready to Inspect Your PCB Gerber Files?
No account creation, no software installation, and 100% private in-browser computation. Launch the editor now to begin inspecting your layers.