LetaProfessional CAD. Local. Yours. Forever.
Leta is parametric CAD for Windows and Linux. Sketch with dimensioning, relations, and a robust constraint solver. Build parts from a fully parametric feature history. Fold, cut, form, and roll sheet metal, and much more. Easily generate flat patterns, and make full drawing packages that are ready for production — in a native app that runs offline and keeps your files on your own disk.
- No account
- Works offline
- A license you keep
Motion studies and exploded views
The seven-cylinder radial engine that comes with Leta as a sample, with its wooden propeller: 160 components placed by 290 mates. A motion study turns the crankshaft through two revolutions, one complete four-stroke cycle, and an exploded view takes the engine apart along its own axes.
The motion study is driven by one motor on the crankshaft’s joint. Gear mates turn the cam ring at a sixth of the crankshaft’s speed in the opposite direction, its lobes lift the tappets through cam mates, and the pushrods, rockers and valves follow with the engine’s valve timing.
Makers. Engineers. Startups.
Leta is user-friendly enough for a casual maker to learn it quickly and use it for any personal project, and capable enough to be used professionally by small- to medium-sized teams.
Design intent, in numbers
Every length, angle and radius can be typed, named and driven by a relation. Parameters, relations and configuration tables are built in. Leta project parameter files define global parameters for entire multi-part projects.
Edits you can trust
All feature edits are fully parametric. A feature that can’t rebuild is marked and explained, and the rest of the part still builds.
Native and quick
Written in C++ with its own OpenGL renderer. An edit rebuilds from the feature you changed, not from the top of the tree.
Yours, on your machine
No account and no cloud. Parts are stored locally, and parts can be encrypted with AES-256.
Design and documentation in one application
Leta covers the mechanical design process from the first sketch to the production drawing: part modeling, sheet metal, assemblies and drawings, with standard file formats for working with suppliers and manufacturers.
Parametric sketching
Sketches are built from lines, arcs, circles, rectangles, slots, polygons, ellipses and splines, and are defined by geometric constraints and driving dimensions. Constraints such as horizontal, parallel, tangent and coincident are inferred as geometry is drawn, and points snap to existing sketch entities and model edges.
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A single dimension command creates linear, angular, radial and diameter dimensions according to the geometry selected, and every value accepts an expression or a named parameter. The solver reports the remaining degrees of freedom and identifies over-constrained conditions before they are applied. Editing commands include trim, extend, divide, fillet, chamfer, mirror, offset and pattern. Model edges can be projected into a sketch, and sketch geometry can be copied between parts or imported from DXF.
Feature-based solid modeling
Parts are built as a regenerating history of features. Solid features include extrude, revolve, sweep and blend, together with thin-wall extrusions, shell, draft and rib. Holes follow ISO and inch standards as simple, counterbored, countersunk, counterdrilled, tapped or tapered holes, with cosmetic or modeled threads.
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Edges can be rounded with constant, variable, conic or partial-length rounds, and chamfered by distance or by angle. Features can be patterned in a line, around an axis, by sketch points or along a curve, and mirrored about one or two planes. Datum planes, axes, points, coordinate systems and curves, including helices and equation-driven curves, provide references for further features. Faces can also be moved directly with push-pull, which is recorded in the history like any other feature.
Sheet metal and flat patterns
Sheet-metal parts are modeled as walls and bends and maintained in the flat state, so the flat pattern is exact at every stage of the design. Features include base sheets from closed or open profiles, edge and miter flanges, hems, jogs, bends along sketched lines, break corners, and cuts that cross bends or are drawn directly on the flat pattern.
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Forming tools produce dimples, louvers, lances and extruded holes. Bend allowance is calculated from a K-factor, a bend deduction or a bend table, with gauge tables and configurable corner reliefs. Flat patterns export to DXF with their bend lines, and sheet-metal parts imported from STEP are rebuilt as native, fully dimensioned features.
Assemblies and mechanisms
Assemblies combine parts and sub-assemblies, positioned with mates such as coincident, parallel, concentric, tangent, distance, angle, symmetric and path, or with joints: revolute, slider, cylindrical, ball, planar and pin-slot, each with optional limits. Gears, rack and pinion, screws, cams, belts and universal joints couple the motion of components, so a mechanism can be dragged through its range of travel or run as a motion study with plotted results.
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Components can be patterned and mirrored, including true opposite-hand parts. Exploded views, section views, interference and clearance checks, and mass properties are available, and bills of materials export to CSV or Excel. Parts can be edited in the context of the assembly, holes and cuts can pass through several parts at once, and large assemblies open in a lightweight mode that loads part data only when it is needed.
Standard hardware and machine parts
Insert Hardware places standard parts in an assembly from a built-in library of 101 families in metric and inch sizes: screws, nuts, washers, spacers, standoffs, set screws, shoulder screws, pins and clips, rivets, O-rings and heat-set inserts, and the parts machines are built from, such as timing pulleys and idlers, roller chain sprockets, ball bearings, linear rails and carriages, lead screws, stepper motors, fans and T-slot framing. The sizes come from manufacturers' and distributors' published catalogs, checked against a second source wherever one exists.
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A part is chosen in a few steps of pictures and placed with a click: on the edge of a hole for a screw, a bearing or a pulley, or on a face for a rail or an extrusion, where a T-slot nut lines up on the nearest slot. Timing pulleys come in eight belt pitches with the bores and belt widths they are sold in, and rails, lead screws and extrusions are cut to any length. Each family is an ordinary Leta part with its sizes as configurations, made the first time it is used. Belts are laid round the library's pulleys on the Routing tab and turn them as the mechanism moves.
Production drawings
Drawings are separate documents linked to their parts and assemblies. Base, projected, section, detail, auxiliary, cropped and broken views are generated with exact hidden-line removal, and flat-pattern views carry bend lines and bend notes. Dimensions remain associative: when the model changes, the drawing updates, and any annotation that loses its reference is reported rather than moved.
Annotation includes ordinate, baseline and chain dimensioning with tolerances, geometric tolerance frames and datum features, surface finish and weld symbols, and hole, chamfer and round callouts taken from the model. Sheets can carry bills of materials, hole, bend and revision tables, and a company title block saved as a template. Drawings export to PDF, DXF, SVG and PNG at true scale, or print directly.
Sample drawing (PDF, 2 sheets)
Parameters, relations and configurations
Any dimension or feature value can be driven by a named parameter or an expression. Relations, written with conditional statements, functions and checks, control dimensions and part properties, and are verified line by line as they are written.
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Configuration tables store variants of a part, such as a range of sizes, which can be switched from the model tree and shown in drawings. Project parameter files define values shared by a group of parts, along with project-wide settings such as the hole standard, material and drawing template.
Import, export and 3D printing
STEP files can be opened as solid bodies or converted into editable features. Extrudes, revolves, holes, rounds and chamfers are recognized, and sheet-metal parts are rebuilt as native flanges with dimensioned sketches. DXF files can be imported into sketches, and models export to STEP, STL, 3MF with colors, OBJ and DXF.
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For additive manufacturing, Leta analyzes draft angles and wall thickness and checks a part against the build volumes of your printers.
Reliability and workflow
Autosave and recovery
Recovery copies are written automatically while you work. After an unexpected shutdown, Leta offers the recovered documents when it next starts.
Encrypted parts
A part can be protected with a password, which encrypts its features, dimensions and names with AES-256. A lost password cannot be recovered.
Build Replay
Steps through a part's history one feature at a time, to review how the part was built or to find the feature affected by an edit.
Analysis
Mass properties with assigned materials, measurement between any two entities with X, Y and Z components, short-edge and geometry checks, and draft and thickness analysis.
Interface
A ribbon with movable, collapsible sections, a model tree, and feature settings in a strip below the ribbon that leaves the model unobstructed. The interface size is adjustable to suit the display.
Updates and file management
Leta checks for updates daily and installs them only when you choose. Numbered file versions and plain-text part files simplify backup and version control.
Windows and Linux
Leta runs natively on Windows and Linux, built from the same source code with the same interface and geometry kernel. A part saved on one system opens on the other and rebuilds to the same model.
Windows 10 and 11
For 64-bit Windows 10 and 11. The installer sets Leta up for one user without administrator rights, or for everyone on the computer, and a portable zip runs from any folder.
Ubuntu 22.04 and later
For 64-bit Ubuntu 22.04 and later, and the systems built on it, such as Linux Mint and Pop!_OS. Leta comes as an AppImage that runs as a single file, or as a folder in a .tar.gz archive.
A license covers Leta on either system, for one person on up to two computers. A macOS version is planned: join the waitlist to hear when it’s ready.
System requirementsPerpetual licensing
Leta will be sold as a perpetual license for one user on up to two computers, with three years of updates included. Versions released during that period remain licensed indefinitely, and further updates can be renewed at a reduced price.
Each computer can run a 30-day evaluation with every feature enabled. Licenses activate without an internet connection or an account.
Licensing detailsDevelopment roadmap
Leta is in beta, with new versions released regularly and documented in the release notes.
Work planned next includes constraints in 3D sketches, weldments of structural shapes and a gear wizard.
Release notesJoin the beta program
Beta builds are distributed by email while the first public release is prepared. Send a short note describing your work and the CAD software you currently use, and you will receive Leta for Windows or Linux and a beta license.
Who makes Leta
I’m a design engineer by trade, and just about everything else in my free time — carpentry, homelab, software, motorsports, and much more. I have nearly a decade of CAD experience (professional and hobby), most of it being in heavy equipment and robotics engineering. I’ve tried to take my favorite elements from each of the programs I’ve used and implement them all into an easy-to-use package with huge capability.
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And to answer the burning question, yes, AI was heavily utilized in creating this software. But only in conjunction with hundreds of hours of my own eyes on every feature, tool, setting, etc., and my own unique ideas and concepts, my own UI design and workflow, not to mention my many friends who have helped me test and debug. I’m glad that modern technology has helped me create something that I can provide at a drastically lower price than the limited and high-priced options currently available.
So please, everyone, enjoy! And feel free to send any and all feedback my way. Every word of it will be read by me and taken seriously.
Tyler Sorensen · support@letacad.com