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About this tool
Answer a few questions to pick between MIT, Apache-2.0, MPL-2.0, LGPL, GPL, AGPL and public-domain licenses.
The Open Source License Chooser recommends an open source license — MIT, ISC, BSD-3-Clause, Apache-2.0, MPL-2.0, LGPL-3.0, GPL-3.0, AGPL-3.0, the Unlicense or CC0 — from four questions about copyleft scope, patent protection, simplicity and public-domain intent. The logic encodes each license's actual terms: MPL-2.0's file-level copyleft (§3.3), LGPL-3.0's linking exception (§4), AGPL-3.0's network clause (§13) and Apache-2.0's express patent grant (§3).
Open Open Source License Chooser on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
Every recommendation cites the specific clause that drives it — copyleft scope, patent grant, network trigger.
Covers permissive, file-level, library, strong and network copyleft, plus public-domain dedications.
Warnings flag real conflicts, like wanting a patent grant from CC0, which expressly reserves patent rights.
Both are permissive, but Apache-2.0 adds an express patent license from every contributor (section 3) that terminates if the user sues over the project, plus a requirement to state significant changes. MIT is about 170 words with a single obligation — keep the notice — but grants no explicit patent rights.
Use AGPL-3.0 when your software is likely to be run as a hosted service: its section 13 requires anyone who lets users interact with a modified version over a network to offer them the source. Plain GPL-3.0 obligations trigger only on distribution, so a SaaS operator can modify GPL code privately without sharing.
MPL-2.0 keeps copyleft at the boundary of individual files: any file you modify that carries the MPL header must be made available under MPL (section 3.3), but you may combine those files with proprietary code in a larger work. It is the common middle ground between MIT-style permissive and LGPL.
You can dedicate it with the Unlicense or CC0-1.0, which impose no conditions at all — not even attribution. Two caveats: some jurisdictions do not recognise public-domain dedication (both licenses include fallback grants for that), and CC0 section 4(a) expressly does not waive the author's patent rights, so projects needing patent safety usually prefer Apache-2.0.