Draw the wiring with real connectors — HarnessLab writes the pinouts, cut list, wire list and BOM for you as you go. Harness and PCB studio for Windows. 100% offline. Pay once, it’s yours.
A quick look at JC HarnessLab — from a real 3D harness and the design studio to wiring, the finished print and the community behind it.
Every time a wire moves, a hand-typed pinout drifts a little further from the drawing. HarnessLab keeps one source of truth — the drawing — and builds every table from it.
Built from the drawing · always in syncThe same flow whether it’s a two-wire pigtail or a full machine harness.
Pick from 76 connector families with real photos, terminals, switches, relays, fuses, dev boards and modules — or build your own from a photo in Connector Studio.
Wire pin to pin, twist pairs, add splices, then paint looms with tees, ties, grommets, convolute and heat-shrink — with every run measured as you draw it.
Ampacity and fuse sizing, open-circuit checks, live pinout tables, a priced BOM and a full revision history — all built from the same drawing, so nothing drifts.
One click builds the PDF, images, BOM, cut list, wire list and project file — titled, numbered and ready for the floor.
Draw the harness, then design the board it plugs into — without switching tools or buying a second license.
Slide in your own numbers. This only counts the time spent typing and re-checking pinouts, cut lists and BOMs by hand — the part HarnessLab fills in from the drawing.
The connectors, presets and checks for the work you actually do.
Deutsch DT/DTM, Metri-Pack, Weather-Pack and GT connectors, relays, fuses and ring lugs.
ISOBUS breakaway, SAE J928, DIN 9680 and HD30 — with CAN pairs that look like CAN pairs.
7-way RV, 4-flat, J560 and ISO 11446 plugs, trailer cord presets and ground studs.
Marine BC5W2 wire on the BOM, battery switches and cable, bilge pumps, float switches and strobes — with battery runtime and voltage drop per run.
M12 circulars, DIN solenoid plugs, terminal blocks, E-stops, limit switches and panel wiring.
Prox and limit sensors, contactors, time-delay and solid-state relays, valves and motors on 24 V — then run Test Sim before the first power-up.
Rendered in HarnessLabESP32, Arduino, Raspberry Pi and 100+ modules with pin guides, then a board you can send to the fab.
XLR 3- and 5-pin for audio and DMX, Speakon, TRS and RCA, speakers and amps, LED strips and strobes — with cut lists for every snake.
Rendered in HarnessLabPortable edition on a USB stick, print-ready sheets and cut lists the bench can build from.
No monthly fee to keep drawing, no forced cloud, no locked file format.
Desktop Installer $129.99 or Portable Edition $149.99 — a one-time purchase. New versions arrive right inside the app.
Draw, check and export with no internet at all. Only the extras go online: the AI assistant (your own key), optional Cloud, and update checks.
Projects save as portable .json files wherever you choose. Exports are standard PDF, PNG, SVG and CSV — plus KiCad and Gerber for boards.
Real feedback from people designing with JC HarnessLab. Read all & leave a review →
Ask questions, share your builds, and grab connector libraries, mods and templates other builders made.
No. The app is a one-time purchase — Desktop Installer $129.99 or Portable Edition $149.99. HarnessLab Cloud is an optional monthly add-on for syncing and teams; you never need it to use the app.
No. Drawing, checking and exporting all work offline. The internet is only used by optional extras: the AI assistant (with your own key), HarnessLab Cloud, and update checks.
The real app with a few limits: up to 5 real parts per drawing (wires, splices, looms, ties and shapes don’t count), a starter set of the library, and 2 exports with a watermark. Board exports, the full package ZIP and the AI assistant are locked. Opening a whole project always works.
Installer: a normal Windows install with a Start menu shortcut (a per-user install works without admin rights). Portable: one program you run from a USB stick or folder — no install, and your settings, shapes and footprints travel with the drive.
PDF prints, PNG and SVG images, BOM, cut list and wire list (CSV), the project file (.json) and a full package ZIP — and for boards, KiCad, Gerber + drill, netlist and 3D images.
Windows 10 and 11 (64-bit). A Mobile Edition for phones and tablets is in development.
The app checks for new versions and installs them from inside the app (Help › Check for Updates). New versions also show up in your account’s Downloads tab.
Still wondering? Visit Support or ask the community.
Pay once, draw forever. Or take the free demo for a spin first.
Start menu install · per-user install without admin rights
Runs from a USB stick · no install · settings travel with you
Drop real photo connectors, paint the loom, twist the pairs and wire the whole thing pin to pin. Lengths measure themselves and the cut list, wire list and BOM are already done when you are.
A five-run implement harness: loom, splice, three face views and two live tables — nothing typed twice.
Switch any connector to its side-view photo and the drawing looks like the bench: the real housing, the real wire side, every cavity numbered where the wire lands. The Inspector puts colour, stripe, gauge, circuit and length on every wire.
CAN, sensor and signal pairs draw as an actual twisted pair between the real connectors — tight, normal or loose pitch, Z or S lay, bowed where you drag it and tagged with its name.
Every run that tees into another becomes one harness. Click a pin on one end, then a pin on another — the circuit is wired, measured along its real path and bought at that length on the BOM.
Draw split loom, braid, tape, heat-shrink or jacketed cable along any route. Branch off the trunk and the tees grow on their own — every segment measures itself.
Drop a mating-face view for any loom connector — or one for every connector at once. Cavities fill with their wire colours and the legend writes itself from your circuits.
Grab any bare lead or ring terminal and drag it exactly where you want it, then choose how each lead is finished. Coverings draw at true wire thickness and ends match the wire’s colour and gauge.
Snap a phone photo of any connector. The background remover runs fully offline — it clears the bench and the shadows and keeps the wires running off the edge. Click where the wires land and it’s a real part: on the sheet, at loom ends and on the BOM.
.jchlib file
PHONE PHOTOAFTER · REMOVED OFFLINE
Housings, terminals, seals, wedgelocks, cavity plugs, splices, ties and wire by cut length all come straight off the drawing. Add manufacturer and internal part numbers once and save them as rules for every drawing.
Every export is a finished, titled sheet — title block, border zones and your company profile with auto-numbered drawings. Preview it dark, light or mono, then build the whole package.
Test Sim turns the drawing into a live electrical model. Press Power and current flows along every wire, fuses heat up and blow, relays pull in and lamps glow — then break it on purpose and see exactly what fails.
Everything below comes from the same drawing — change a wire and every list follows.
Give parts a current draw and undersized wires get flagged before they get hot.
Left, right, both or none, with arrowhead styles — dimensions that read like a real print.
Manufacturer and P/N for wire, braid, loom and any Auto BOM line.
Save any assembly — a fuse block, a lamp pigtail — and drop it into the next job.
Commit, compare and restore. The revision log exports to CSV and rides along in the package.
Cut list, from/to, splices, segments and crimp tables that follow the harness as it changes.
Covering, trade size, tracers, shield, conductors and both ends — save your own presets.
Low-code .jchlmod add-ons for exports, BOM lines, design rules and more.
Draw the circuit with real symbols and named dev-board pins, push it to a board, route it and check it, spin it in 3D — then send Gerbers and a drill file straight to the fab house.
A 555 flasher / load driver on a 60 × 40 mm board: smart-placed, routed on two layers with a GND plane, ten vias and four mounting holes — check passed.
This is the same 555 board, layer by layer, drawn from the app’s own geometry. Each layer leaves as its own Gerber in the fab ZIP — hover one to lift it out.
236 symbols, each with an SMT or through-hole package — passives, diodes, transistors and MOSFETs, logic gates and flip-flops, regulators, op-amps, the 555, CAN and RS-485 transceivers, headers and terminal blocks. Wire pin to pin in colour; references number themselves.
Auto-place puts the connectors on the board edges and keeps the 555 with its timing parts. Route all then works both copper layers and vias, widens the power nets and pours ground on the bottom with stitching vias — and the check tells you what’s next.
Symbols made in both packages switch with one click in the Inspector: SOIC-8 or DIP-8, 0805 or axial, SMA or DO-41, DPAK or TO-220. Switch one part or the whole board — the footprint, the BOM line and both 3D views follow.
Arduino, the ESP32 family, ESP8266, Raspberry Pi and Pico, STM32 Blue Pill, Teensy and more — plus chargers, converters, IMUs, displays, relay boards, motor drivers, GPS and CAN modules.
Check fit and clearance in 3D — hero, isometric, top, front, side, low and bottom views; toggle parts, copper, silk and standoffs, pick a backdrop and lighting, then save an image or record a turntable video for the customer or the build sheet.
Package RS-274X Gerbers for all seven layers plus an Excellon drill file, zipped and ready for any fab house. Preview every layer before you send it.
Type what you need — “ESP32 switching a 12 V relay through an NPN with a flyback diode” — and the assistant drafts the parts, the wires and an explanation. Review the plan, then add it to the canvas.
Straight from the board you just checked — no converters, no second program.
Generate a starting footprint or build it pad by pad; import and export between PCs.
Flip to the bottom side to place and route there.
Check every Gerber layer on its own before it leaves.
Load someone else’s Gerbers as overlays, align and convert to editable objects.
Pour zones, add silkscreen text and graphics, place mounting holes.
Rectangle, rounded or custom — drag outline corners and set a corner radius.
Power nets route wider automatically under your design rules.
Let the assistant fill in BOM detail and write the firmware to go with it.
Every dialog is designed for the job — drag or swipe through a few of them.
Switch workstations and the library and tools change to suit the job — nothing on your sheet moves. Draw the controller and the harness that feeds it in one drawing, one BOM and one package.
Connectors, terminals, switches, power parts, Loom Studio V2 and cut lists.
Schematic symbols, dev boards, modules, board layout and Gerbers.
Everything at once for mixed jobs — one sheet, one BOM.
Installs in a minute, runs entirely on your machine — try it free with the demo first.
Five steps, one file, no internet required. Place the parts, wire them, dress the cable, check it and ship the packet — without ever leaving HarnessLab.
Start from a library built for harness work — or bring your own. Search, favorite and drop parts onto the sheet; references number themselves as you go.
Drag from a pin to its mate, or tap-tap. Every wire carries its color, stripe, gauge, circuit ID, length and signal label, and the routing stays tidy on its own.
Paint the real cable in Loom Studio: split loom, braid, tape, heat-shrink or jacketed cable, with branches, ends and fittings — and lengths that measure themselves.
HarnessLab watches the electrical side while you draw, so problems turn up on screen instead of on the bench.
Every output is a finished sheet: title block, border zones, your logo and an auto-numbered drawing. One click bundles everything the floor and purchasing need.
REAL EXPORT PREVIEWSame harness, same five steps — captured straight out of JC HarnessLab v8.4.1.
Exported locally, named the way you set in Settings, and ready to hand off.
.json files you can back up and version.Try the free demo, or buy once and keep it forever.
Pay once and own the app — add Cloud storage, teams and HarnessLab AI whenever you need them.
Free HarnessLab account required — you’ll sign in first.
Installs to your PC with a Start menu shortcut. The right pick for your own workstation.
Free HarnessLab account required — you’ll sign in first.
One executable on a USB stick. Plug into a locked-down machine on the floor and work.
Want a ping the day it ships? Tap the button and leave your email.
The app is pay once, use forever.
Add it when your team needs it.
Until you choose to sync them.
Keep projects and part libraries in sync across your PCs and share them with your team — right from the app’s ☁ Cloud button. Monthly, cancel any time. Your HarnessLab license stays yours either way.
Free HarnessLab account required — you’ll sign in first.
Free HarnessLab account required — you’ll sign in first.
Teammates you invite don’t need their own plan — just a free account and their own HarnessLab license. Cancel any time: your space turns read-only so you can still download everything.
How Cloud works →The ✨ assistant in HarnessLab, ready to go — no API key, no setup. Design, edit, review and document your drawing in plain English. Monthly, cancel any time.
An add-on for JC HarnessLab (Installer or Portable Edition) — subscribe with the same email you bought HarnessLab with. You’ll sign in to your free HarnessLab account first.
ESP32 switching a 12 V relay with a flyback diode, plus a status LED.
Here’s a plan for your sheet:
Pay once for HarnessLab and keep it. Add Cloud or the AI assistant only if you want them — monthly, cancel any time.
Same HarnessLab, two ways to run it. Both are yours to keep.
Purchases need a free HarnessLab account — you’ll sign in first so your download, license and updates land in one place. The demo needs no account.
Optional monthly add-ons that work with either edition. Cancel any time — the app stays yours.
Pick what you need and see exactly what you’ll pay — today and each month.
Each item is its own secure checkout. Start with the app, then add plans here or from your account any time.
The app does the work. Add-ons are there when you outgrow one PC or want a co-pilot.
| Installer | Portable | + Cloud | + AI | |
|---|---|---|---|---|
| Design | ||||
| Harness, schematic & PCB design | ||||
| Loom Studio & Connector Studio | ||||
| Live tables, BOM & quotes | ||||
| One-click full export package | ||||
| Running it | ||||
| Works fully offline | ||||
| No install or admin rights | with Portable | with Portable | ||
| Updates within the major version | ||||
| Cloud & teams | ||||
| Sync projects & libraries across PCs | ||||
| Version history & 30-day trash | ||||
| Shared team space & roles | Team plan | |||
| AI assistant | ||||
| ✨ Assistant with your own API key | ||||
| ✨ Assistant with no API key needed | ||||
| Price | $129.99 | $149.99 | from $6.99/mo | $9.99/mo |
No. The Installer and Portable Edition are one-time purchases — pay once and keep using them. Only the optional Cloud and AI add-ons are monthly, and you can cancel those any time.
Same application, different delivery. The Installer sets HarnessLab up on your own PC with a Start menu shortcut. The Portable Edition is a single program you run from a USB stick on any shop or lab PC, with no install and no admin rights.
Your free HarnessLab account is where your download, license, updates and any Cloud or AI plan live. Signing in first means everything lines up with the same email. The free demo needs no account.
Your cloud space turns read-only, so you can still download everything. Your HarnessLab license and the files on your PC aren’t affected.
No. The assistant also works with your own Anthropic or OpenAI API key at no extra cost — you pay your provider directly. HarnessLab AI is for people who don’t want to set up a key.
Yes — your purchase includes updates within the current major version.
Try the free demo, or get HarnessLab and keep it for good.
Your receipt is in your inbox now, and your download link follows by email shortly. Here’s how to get running.
Your payment receipt arrives right away. We send your download link for JC-HarnessLab-Setup.exe by email shortly after — usually within a few hours. Check spam if you don’t see it, and make sure the email you paid with is one you can reach.
Installer: double-click JC-HarnessLab-Setup.exe and follow the prompts.
Portable: unzip the folder to your USB stick and run the .exe inside. Windows SmartScreen may ask first — choose More info › Run anyway.
Launch it from the Start menu, the desktop shortcut, or straight off the stick. No sign-in, no internet needed — it runs entirely on your machine.
A ten-minute walkthrough, start to finish.
Every key, by mode.
149 guides, searchable.
Real feedback from people designing harnesses and boards with JC HarnessLab — and a place to leave your own.
Using JC HarnessLab? Be the first — your review will appear right here.
Purchase history, re-downloads and the latest updates — all in one place.
Haven’t bought yet? See pricing or try the free demo. You can create an account first — purchases made with the same email show up automatically.
Always the newest build of every edition you own — download it again whenever you need it.
| Order | Date | Product | Total | Status |
|---|
Your HarnessLab AI and Cloud plans — when they renew, the card they use, and cancel or resume.
Checkout uses this account’s email so your plan links automatically. Just subscribed? Press Refresh my plan. How Cloud works
Open and save straight from the app’s ☁ Cloud button, keep 10 versions of every file, and share connector libraries with up to 4 teammates.
Check out with this account’s email so the plan links up. Just subscribed? · Compare plans
Who has the AI plan (paid or complimentary) and how much each account uses — by month, against the monthly allowance. Give complimentary AI from an account’s page.
Everyone who pressed “Email me when Studio updates” on the Studio page — names, emails, sign-up dates and recent activity. Admins only.
Publish new builds of the free demo and JC Harness Studio — upload the installer or paste a link. Every demo button, the demo’s update check and the Studio download button get it, no redeploy.
Change prices and Lemon Squeezy checkout links, and run a sale — crossed-out prices, sale prices, savings and a countdown on the product cards.
The promotion bar above the menu, the “NEW” badge on the home page, and News posts — create, edit, schedule and style them, with a live preview.
See every review with the account that posted it, reply publicly as the team, and hide or delete ones that don’t belong.
Add, edit, reorder or hide the release notes on the Support page — highlights, full notes, Latest and Coming-soon tags, with a live preview.
Admins: . Super admins come from the ADMIN_EMAILS setting in Netlify (default: the site owner’s email) and can grant admin access to other verified accounts.
Ask questions, share your harnesses and help each other build better.
Guides, tutorials, and answers to keep your projects moving.
Set up, learn the basics, and create your first harness.
View guides →Tools, techniques, and best practices for clean designs.
Explore topics →Create PCB outputs, export files, and integrate with other tools.
Learn more →Yes — completely. HarnessLab installs and runs on your own machine. No account, no internet connection, and no cloud service is required at any point, including exports. HarnessLab Cloud is an optional add-on for syncing and teams.
Dimensioned drawings (PDF, SVG, PNG, DXF), wire lists and BOMs (CSV/XLSX), Gerber RS-274X and Excellon drill files for PCBs, plus KiCad-compatible schematic and harness output.
Wherever you choose. Projects save as a single portable project file on your own disk — nothing is uploaded, and you can back them up or version them like any other engineering file.
Use Save project (.json) — you pick the folder, and the whole drawing, including its revision history, is written to that one portable file. Nothing is stored in the cloud. Back it up or version it like any other engineering file, and use Save As to branch a design.
76 connector families with real photos — Deutsch (DT, DTM, DTP, HD10, HD30, DRC and more), Metri-Pack 150/280/480/630, Weather-Pack, Aptiv GT, Molex MX150 and Micro-Fit, JST, AMPSEAL, Amphenol, Sumitomo, trailer and ag connectors, plus USB, RJ45, D-Sub and other everyday connectors — along with 89 switches, terminals and power parts, 36 dev boards, 105 modules and 236 PCB symbols. Anything missing? Build it from a photo in the Connector studio. The full list is in the parts library guide.
Yes. Loom Studio paints cable runs in split loom, braid, tape, heat-shrink, spiral wrap or jacketed cable, with tees and branches, real connector ends, ring lugs, bare-wire breakouts, ties, grommets, P-clamps and flags — and it measures the lengths for you. Select two or more wires and draw them as a real twisted pair with an adjustable twist pitch.
Your purchase includes updates within the current major version. HarnessLab is actively developed — recent builds added Loom Studio, the Connector studio, live tables, Settings with a company profile, and a one-click full export package. The app has no subscription and no forced upgrade; the version you install keeps working.
Same application, different delivery. The installer sets HarnessLab up on one PC with a Start menu shortcut — right for your own workstation. The portable edition is a single executable you run from a USB stick or a network folder: no installation, no admin rights, nothing left behind on the host machine. Techs who move between shop and lab PCs, or work on locked-down company machines, want the portable one. A mobile edition for phones and tablets is in development — the Coming Soon card on the pricing page takes sign-ups.
One purchase covers your personal installs and includes updates within the current major version. The app license has no subscription and no seat check-in.
An optional monthly add-on. Cloud Solo ($6.99/mo, 10 GB) syncs your projects and part libraries across your PCs; Cloud Team ($19.99/mo, 50 GB) adds up to 4 teammates with roles, shared libraries and “who’s editing” locks. You open and save from the app’s ☁ Cloud button or from your account page. Cancel any time — your files stay downloadable. How it works
Windows 10 or 11, 64-bit, and about 300 MB of disk space. HarnessLab is a desktop application — you run the installer once and launch it from the Start menu like any other program.
Our team is here to assist.
Every purchase includes updates within the current major version. Here’s what has landed.
Send us a note and we’ll get back to you within one business day.