MeshOptimiserBeta Download

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Everything, from the first download.

98 short articles, written for someone who has never opened a CAD file in a browser. Start at the top and read down, or search.

Start here

What the app is, what it needs, and how to get from a download to your first model on screen.

  1. What MeshOptimiser isA free app that runs on your own computer. It turns a heavy CAD file into a light 3D file and lets you inspect, clean up and export it.
  2. Words you will meetA plain-language glossary: STEP, mesh, triangle, GLB, instancing, decimation, WebGPU, virtual environment and the other terms these pages use.
  3. What you needWindows or macOS, Python 3.10 to 3.12, a recent browser and about 2 GB of free disk space. How to check and install Python.
  4. Download and unzipOn Windows, one installer does it all. For macOS, or to do it by hand, get the zip and unpack it into a normal folder.
  5. Start it the first timeDouble-click the launcher for Windows or macOS. What the first run sets up, how long it takes, and what you see when it is ready.
  6. Install it as an app windowSince v0.13.0 the app opens in its own window. You can also install it for a desktop shortcut, and fold its title bar away.
  7. Open your first fileDrop a file on the window. What the import settings mean, what conversion does, how to follow its progress, and where the result is kept.
  8. Stop, restart and updateQuit the app cleanly, start it again in a second or two, and move to a newer version without losing your settings.

Install and set up

Every step from the download to a computer that is ready to work: Windows and macOS, the first session, the optional extras, shortcuts, moving or removing the app, and a fix for each message the launcher can print.

  1. Install on Windows, step by stepOne double-click installs MeshOptimiser on Windows 10 or 11: it downloads the app, adds a shortcut, checks for Chrome and starts it. The zip way, step by step, follows for those who prefer it.
  2. Install on macOS, step by stepFrom the zip to a working app on a Mac: Python, the first run, the one-time macOS permission prompt, and what you should see at every step.
  3. Set it up after installingA checklist for the first session: check the renderer, choose the units, set the look and the performance options, and know where your settings are kept.
  4. Add gltfpack for smaller filesAn optional free tool. With it on your PATH, the converter compresses its GLB files with Meshopt, which can make them many times smaller. How to install it and how to check.
  5. Add a shortcut or an iconStart the app from the desktop, the Start menu or the Dock instead of opening the folder every time. Windows and macOS, with and without the launcher window.
  6. Move, copy or remove the appMove the folder, put it on another computer, keep what matters, or remove everything it ever stored, including the settings in your browser.
  7. Install problems, message by messageEvery message the launcher can print when the setup stops, what it means, and exactly what to do about it. Windows and macOS.

Getting your model out of your CAD program

MeshOptimiser opens STEP files. How to save one from Inventor, Onshape, Creo and Rhino, with the options that matter.

  1. Native CAD files: export a STEP file firstMeshOptimiser opens STEP, not SolidWorks, Inventor, Creo or CATIA files. Why, which STEP version to pick, and where to find the steps for your program.
  2. How to export a STEP assembly from Autodesk InventorSave an Inventor assembly as one STEP file with Save Copy As, pick AP214, and learn what Shrinkwrap can do for a very large assembly.
  3. How to export a STEP assembly from OnshapeExport an Onshape assembly or Part Studio as STEP by right-clicking its tab, and why STEP is a better start than Onshape’s own glTF export.
  4. How to export a STEP assembly from PTC CreoSave a Creo assembly as one STEP file with Save a Copy, set the application protocol and keep Export assembly as on Single File.
  5. How to export a STEP file from RhinoExport selected Rhino objects as STEP with File, Export Selected: which protocol keeps colours, what happens to black objects, and what to do with meshes.

Find your way around

The window, the mouse, selecting, hiding, the parts tree, search, undo, tabs and settings.

  1. The windowA tour of the screen: the top bar and tabs, the parts tree, the 3D view and its toolbars, the cards on the right, the drawers, the status bar and how to resize it all.
  2. Move the viewOrbit, pan and zoom with the mouse, frame a part with F, and switch between the camera, Top, Front and Side views.
  3. Select partsClick, add with Shift, toggle with Ctrl, drag a box, or let the app select by shape, colour or name.
  4. Hide, isolate, show allHide parts that are in the way, look at a few parts on their own, and bring everything back with one key.
  5. The parts treeSearch, rename, group and reorder the parts of a model, rename many at once, and flatten a hierarchy that is deeper than you need.
  6. Organise the tree: groups, sorting and pickingPick groups and parts together, take a group out of the tree without losing what is in it, flatten, sort and move groups.
  7. Search and commandsPress Ctrl + K or Shift + C to find any command, part, library part or setting by name, turn a switch without leaving the list, and work out a sum or convert a length.
  8. Quick wandHold Q and a ring of commands opens under the pointer. Flick toward one and let go.
  9. Undo and redoEvery editing action can be taken back with Ctrl + Z. What counts as one step, and how to go back to the file as it was opened.
  10. Scene tabsEach tab is a scene of its own. Open several files side by side, drop a file to add it or open it in a tab, drag tabs into order, and save from the tab’s dot.
  11. SettingsOne window with its sections and a search. What each section holds, in a sentence or two, from the start-up options and the search to the look of the interface.
  12. The help windowThese articles also live inside the app. Press F1 to open them, with a search, and read them with no internet connection.

Make it lighter

The tools that remove triangles and parts, one at a time, and a sensible order to use them in.

  1. How to read the numbersWhat a triangle count tells you, where the app shows it, how to find the heaviest parts, and how to see what your work has saved.
  2. Heavy partsA list of the parts that hold the most triangles, heaviest first, with a count beside its title. Tick the ones you do not need and delete them in one step.
  3. Batch optimise a folderOptimise every model in a folder, one after another, and find the lighter copies in the exports folder.
  4. Smart optimisev1One card, one button: every clean-up the app has, run one after another on the whole scene. Choose how far to go, read the plan, press Optimise.
  5. Delete small partsv1Remove the screws, washers and clips that are too small to matter, with a slider and a preview of what will go.
  6. Select hidden partsv2Find every part that cannot be seen from outside the model, such as screws inside a housing, and delete them in one step.
  7. Remove hidden facesv1Delete the faces that can never be seen from outside, such as the inside of a housing or the faces where two parts press together.
  8. Fastenersv6Find every bolt, screw, nut and washer by its shape, whatever the parts are called, then isolate or delete them in one step.
  9. Stacked copiesv1Find parts that sit exactly on top of an identical copy of themselves, drawn twice, and remove the extra ones.
  10. Remove holesv15Close bolt holes, slots, pockets and lettering in flat faces. Each closed hole removes the triangles of its walls.
  11. Remove floating piecesv2Delete the small loose pieces of a part that touch nothing: a plug, a shaving, a dot of a thread. The biggest piece of each part always stays.
  12. Triangulation: Untriangulate and Triangulatev3Join the triangles of each flat face into one polygon and take away the vertices in its middle, or go back to even triangles. The shape stays as it is.
  13. Splitv6Take apart a mesh that arrived as one piece but is really several separate solids, or cut it into its faces, so each can be selected on its own.
  14. Smart fitv3Replace a detailed part with a simple stand-in of the same size and position: a box, a cylinder, a few boxes, or blocks that keep its outline.
  15. Decimatev5Remove a share of the triangles from the selected parts while keeping their shape. Choose a percentage or a target, and preview first.
  16. Fit to budgetv4Type the number of triangles the whole scene may have. The densest meshes are reduced first until the total fits.
  17. Quick fixes and tidying upSmall one-click repairs: remove empty parts and empty groups, fix shading, recentre the model and make moves permanent.
  18. Model inspector: what the model is, and what is wrong with itOne window that shows what is in the model and finds the faults in it: faces turned the wrong way, holes, doubled triangles. Each fault has a button that fixes it.
  19. Fix normals: faces that point the wrong wayFind faces that are turned the wrong way and turn them right, in one tap, without guessing.
  20. A sensible order to work inA suggested routine for a first clean-up: look, delete what is not needed, simplify what remains, check, save and export.

Look and arrange

View modes, materials, moving and measuring, editing the points, edges and polygons of a part, standing a model on the floor, and adding parts.

  1. UV layout: how a texture sits on a partSee how the picture on a part is laid out, and where it overlaps, runs outside its square or stretches.
  2. CAD faces and edges from a STEP fileA STEP file knows its real faces and real edges. MeshOptimiser keeps them, so the outlines are the ones the designer drew.
  3. Quick colour wheel: colour a part without a dialogHold a key, move, click. The selected parts take the colour as you go.
  4. View modesSix ways to draw the same model: solid, wireframe, X-ray, heatmap, clay and CAD. One key each, plus the Shading card for the clay and CAD looks.
  5. Colours and materialsOpen the materials dock to see every material in the scene, recolour all the parts that share one, assign a material with a button or by dragging it onto a part, and let the dock float as a window.
  6. Several colours on one partGive some faces of a part a colour of their own. The part stays one part, and the colours go with it into every file.
  7. The pivot of a part: Centre pivotCentre the pivot of a part, reset its rotation, move the pivot or the object to the origin, the selection or the view, align it, and reset the scale.
  8. Move, rotate, scale and measureUse the gizmo to move, turn and resize parts, drag a part over other surfaces with Dynamic place, type exact values in the transform card, and measure the distance between two points.
  9. Simplify round facesFewer facets on the cylinders, cones, spheres and tori of a part from a STEP, as coarse as a deviation allows. The flat faces follow at the rims, and the part keeps its CAD faces.
  10. Remove thicknessMake a thin-walled part the one surface it stands for: a hollow pipe keeps its outside, a part bent from sheet keeps one face.
  11. Remove fillets and chamfersTake the small rounds and chamfers off a part that came from a STEP, and get its sharp edges back. The faces on either side are extended until they meet.
  12. Mend a mesh: Close cracks, Remove slivers, Fill mesh holesThree small repairs for meshes that came out of a CAD program: close the hairline cracks between faces, get rid of needle-thin triangles, and patch openings so the patch follows the curve round them.
  13. Reshape a mesh: Isotropic remesh, Smooth surface, Convex hull and moreRebuild a part’s triangles: even and well shaped, smoothed without rounding the edges, as a simple convex shell for a game engine, or with its overlapping bodies joined into one.
  14. Union, Subtract and Intersect partsJoin parts into one, cut one part with others, or keep only where they overlap. Exact, on closed parts, with the first part you picked as the one that changes.
  15. Voxel remeshRebuild a part as one clean, closed, even surface, the way Blender’s Voxel remesh does. Overlapping bodies become one and hollows inside are filled. Good for a watertight stand-in of a messy part.
  16. Round parts: Fill round grooves, Fill solid round, BeltRebuild a turned part (a spool, a bushing, a pulley) clean from its profile, with its ridges and grooves filled. A fan or a gear can be made one solid round shape, and a drive belt loses its ribs.
  17. Remove lettering and logosTake text and logos off parts, however the CAD program made them: raised or engraved in the part’s own surface, or modelled as separate little bodies laid over it.
  18. Edit mesh: points, edges and polygonsv4Pick and change the pieces a part is made of: its points, edges and polygons. Move, delete, dissolve, planarize, straighten, weld, fill and extract them, from a bar at the right of the view.
  19. Align to floorStand a model upright on the grid, centred over the origin, when it arrived on its side or far away from the centre of the scene. A small drawing shows the result first.
  20. Align partsLine the selected parts up along an axis, or space them evenly, with one press. Each press is one undo step.
  21. Exploded viewPush the parts of an assembly apart with one slider, choose the directions, and put them back with one click.
  22. Animate (alpha)Make parts or groups spin, swing, shake, travel along a path or oscillate like a piston, watch it on a timeline, and take it out as a video or inside a GLB.
  23. The parts library and shapesAdd standard parts to a scene from a drawer under the viewport: 112 bolts, nuts, pipes, profiles, machine parts, electronics and brackets. Look at a part and set its size before it goes in.
  24. Draw lines and shapesDraw curves, rectangles, circles and polygons on the floor or on a face, edit their points, and use them as paths.
  25. Sweep a profile along a linev2Turn a path and a profile into a solid part: a pipe, a rail, a ring.
  26. ScreenshotsSave a picture of the viewport as a PNG, at the size of the view or at any resolution up to poster size.
  27. Section viewCut the whole scene with one plane to look inside it: everything on one side is cut away and the inside of the cut is drawn flat.
  28. Photo modeDraw the model the slow, pretty way, with studio light, a soft floor shadow and a few picture effects, and save a PNG up to four times the size of the view.

Work with Claude

Connect the app to Claude, what Claude can do in it, and what stays in your hands.

  1. Work with ClaudeLet Claude look at the open scene, find what is heavy and do the clean-up in the app, asking you first.
  2. Claude mode (alpha)Hide the app and follow what Claude does as a feed of messages, calls and pictures, with the model beside it.

Save and export

Keep your work as a scene, or write a file for another program.

  1. Save a sceneSave your work as a scene file so you can carry on later. What a scene file is, how to name it with the file-name buttons, and how it differs from an export.
  2. Get your scene back after a crashWhile a scene has changes that are not saved, a copy is kept inside your browser. If the app crashes, it offers the scene back the next time it starts.
  3. ExportWrite the model to GLB, glTF, FBX, USDZ, OBJ, STL, PLY or a parts list, name the file, and set the scale, up axis and origin the next program needs.
  4. Which format should I chooseA short guide by purpose: the web, Blender, game engines, AR on an iPhone, 3D printing, or a parts list.
  5. Notes: tasks on the model, with comments, sent with the sceneA note is a task about a place or a part: a title, what it is about, who it is for, how urgent and when, with comments under it. Save the scene and whoever opens it sees every note, answers it and signs off, and the file shows who did what.

Common jobs, start to finish

Three jobs people come here to do: convert a STEP file to GLB, take the bolts out of an assembly, and make a model safe to send to a customer.

  1. How to convert a STEP file to GLBConvert a STEP CAD file to a small GLB for the web, on your own computer and for free. The model is never uploaded. Drop it in, check it, export.
  2. How to remove bolts and screws from a STEP assemblyTake the bolts, screws, nuts and washers out of a CAD assembly before it goes on the web. Select one, select the rest, check, delete, and undo if needed.
  3. How to make a CAD model safe to send to a customerShow your product without handing over your design. Remove hidden parts and fasteners, simplify what is left, clean the names and export a small GLB.

Reference

Every shortcut, every command-line option, the file formats and what is in the folder.

  1. Keyboard shortcutsEvery keyboard shortcut and mouse action in MeshOptimiser, grouped by what it does.
  2. The command-line converterConvert STEP files to GLB without opening the viewer. How to run step2glb.py, and what every option does.
  3. File formatsWhich files the app opens and which it writes, and what each format keeps: the parts tree, materials and vertex colours.
  4. Files in the folderWhat the files and folders inside the MeshOptimiser folder are for, which ones you use, and which ones to leave alone.
  5. Privacy and offline useMeshOptimiser runs on your own computer. What stays local, when the internet is used, and what the browser remembers.

Help

What to do when something goes wrong, and answers to common questions.

  1. TroubleshootingFixes for the usual problems: Python not found, a blocked launcher on macOS, missing modules, a blank view and slow conversions.
  2. Frequently asked questionsShort answers: cost and licence, privacy, browsers, file sizes, whether Python is needed, and where to report a bug.
  3. Self-testFor the curious: the app can test itself. One address runs a suite of checks inside the live app and reports the results.

Pick how you run it.

In your browser

MeshOptimiser Web

Try the app in a tab. Nothing to install.

LaunchWhat is it

On your machine

MeshOptimiser

The full app. Windows and macOS.

Download v0.37.3What is new
Free
Free
Browser tab
Your computer
Files stay local
Files stay local
STEP to GLB
STEP to GLB
Clean-up tools
Clean-up tools
Part library
Part library
Folders and CLI
Folders and CLI
Claude
Claude
Works offline
Works offline

Web opens a sample gearbox first and needs a window 960 px wide. Best in Chrome: Safari on a Mac can lag.