GPLv3, MIT, Apache2.0 — an overview

Did you know that Open Edu­ca­tional Resources (OER) have their ori­gins in soft­ware devel­op­ment? Open source licenses (OS licenses), which orig­i­nated in the free soft­ware move­ment, were the first
open licenses of their kind.

Openly licensed soft­ware is open source, i.e. the pro­gram code can be freely mod­i­fied. This fea­ture makes open source soft­ware par­tic­u­larly attrac­tive for teach­ing and learn­ing. By using OS soft­ware, not only can license costs be saved, but more inde­pen­dence can be gained and trans­parency pro­moted. Many OS pro­grams can also be used free of charge, i.e. no fee has to be paid for the ser­vice (not to be equated with license costs), guar­an­tee bet­ter data pro­tec­tion and are often in no way infe­rior to con­ven­tional com­mer­cial solu­tions. Since Cre­ative Com­mons (CC) licenses are not suit­able for licens­ing soft­ware, twillo has expanded its license pool to include the three best-known OS licenses in their cur­rent ver­sions: GPLv3, MIT and Apache 2.0. What do these licenses have in com­mon and what are their spe­cial fea­tures? What rights and oblig­a­tions do they trig­ger? Which licenses are they com­pat­i­ble with? We have com­piled this infor­ma­tion for you in the fol­low­ing overview.

Common features of the OS licenses

Allowed:

• free dis­tri­b­u­tion of the (derived) soft­ware
• Free mod­i­fi­ca­tion of the source code

Not per­mit­ted:

• Dis­crim­i­na­tion against persons/groups of per­sons
• Restric­tions with regard to the area of appli­ca­tion
• Con­di­tions for the acqui­si­tion of rights to the derived soft­ware: e.g. trans­fer only in the soft­ware pack­age; use only with cer­tain tech­nolo­gies, etc.
• License fees for the grant­ing of rights to use the soft­ware

There are no offi­cial trans­la­tions of the OS licenses. The Eng­lish license text is author­i­ta­tive. In the case of mul­ti­lin­gual soft­ware, the license notice should be in Eng­lish. Appli­ca­tion exam­ples for indi­vid­ual licenses can be found in the OS Ini­tia­tive’s list of open source licenses.

Special features of OS licenses

GPLv3

• A restric­tive OS license
• Strict copy­left: Com­bi­na­tions with the source code of other soft­ware must be placed under GPL; the strict copy­left does not apply to other changes to the source code.
• The mod­i­fied source code must be dis­closed if the soft­ware is dis­trib­uted.
• Con­tains a patent clause accord­ing to which patents on fur­ther devel­op­ments — if nec­es­sary — are co-licensed, i.e. no license pay­ments may be demanded for patents (cf. MIT).
• All changes to the orig­i­nal soft­ware must be listed (doc­u­mented) in detail.
• The orig­i­nal copy­right and copy­right notices may not be removed/altered. No con­di­tions devi­at­ing from the orig­i­nal copy­right notice may be included for derived works.
• Effec­tive­ness of the license (its cen­tral clauses) in Ger­many has been con­firmed by sev­eral courts.

MIT

• A per­mis­sive OS license
• No copy­left: mod­i­fied parts of the soft­ware may be placed under a dif­fer­ent (e.g. pro­pri­etary) license. Unmod­i­fied parts of the soft­ware remain under MIT, inso­far as they can be used inde­pen­dently.
• The mod­i­fied source code does not have to be dis­closed if the soft­ware is dis­trib­uted.
• No patent reg­u­la­tion. Atten­tion! License pay­ments may be required for patented soft­ware dis­trib­uted under MIT. In this case, the use of the soft­ware is no longer free of charge.
• Changes to the orig­i­nal soft­ware do not have to be listed.
• Since the MIT license text itself is not copy­righted, any­one is free to mod­ify it for their own pur­poses and set their own con­di­tions for use. For this rea­son, there are many versions/modifications of the license. These are prac­ti­cally iden­ti­cal to the orig­i­nal license. A com­par­i­son is nev­er­the­less rec­om­mended.
• Easy han­dling short, con­cise license text

Apache 2.0

• A per­mis­sive OS license
• No copy­left: mod­i­fied parts of the soft­ware may be placed under a dif­fer­ent (e.g. pro­pri­etary) license. Unmod­i­fied parts of the soft­ware remain under Apache 2.0, inso­far as they can be used inde­pen­dently.
• The mod­i­fied source code does not have to be dis­closed if the soft­ware is dis­trib­uted.
• Con­tains an explicit patent pro­vi­sion: no license pay­ments may be demanded for patented Apache soft­ware (cf. MIT).
• All changes to the orig­i­nal soft­ware must be listed (doc­u­mented) in detail.
• The orig­i­nal copy­right and copy­right notices may not be removed/altered. Con­di­tions devi­at­ing from the orig­i­nal copy­right notice may be included for derived works.
• Adap­ta­tions (= derived works) may only bear the name “Apache” with the writ­ten per­mis­sion of the Apache Fon­da­tion.

Rights of the OS licenses

GPLv3

• Dupli­cate
• Spread
• Edit
• Com­mu­ni­ca­tion to the pub­lic and mak­ing avail­able to the pub­lic
• (Com­mer­cial) dis­tri­b­u­tion of the mod­i­fied soft­ware

MIT

• Dupli­cate
• Spread
• Edit
• Com­mu­ni­ca­tion to the pub­lic and mak­ing avail­able to the pub­lic
• (Com­mer­cial) dis­tri­b­u­tion of the mod­i­fied soft­ware
• Sub­li­cens­ing
• Free choice of license for fur­ther devel­op­ments
• Inclu­sion of own license con­di­tions, copy­right notice for the use, repro­duc­tion and dis­tri­b­u­tion of the derived work

Apache 2.0

• Dupli­cate
• Spread
• Edit
• Com­mu­ni­ca­tion to the pub­lic and mak­ing avail­able to the pub­lic
• (Com­mer­cial) dis­tri­b­u­tion of the mod­i­fied soft­ware
• Sub­li­cens­ing
• Free choice of license for fur­ther devel­op­ments
• Inclu­sion of own license con­di­tions, copy­right notice for the use, repro­duc­tion and dis­tri­b­u­tion of the derived work
• Atten­tion! Orig­i­nal instruc­tions must always be retained!

Obligations of the OS licenses

GPLv3

• Applies both to the use of the orig­i­nal soft­ware and to your own fur­ther devel­op­ments:
• Enclose the orig­i­nal license text (in paper form/as a text file)
• Attach a suit­able copy­right notice (e.g. ©2021 (name of copy­right holder). Exist­ing copy­right notices may not be removed.
• Attach a dis­claimer notice. Exist­ing notices may not be removed.
• Infor­ma­tion on what was processed and when
• Com­bi­na­tions with the source code of other soft­ware under GPLv3
• The entire source code, includ­ing pro­pri­etary parts, must be dis­closed:
  • pub­lish or
  • on a data car­rier or
  • make avail­able for down­load from the same web­site (for online dis­tri­b­u­tion)

MIT

• Applies to the use of the orig­i­nal soft­ware, but not to fur­ther devel­op­ments:
• Include the orig­i­nal copy­right notice, the orig­i­nal license notice and the dis­claimer of war­ranties and lia­bil­ity in all copies or sub­stan­tial por­tions of the Soft­ware

Apache 2.0

• Applies both to the use of the orig­i­nal soft­ware and to your own fur­ther devel­op­ments:
• Attach license terms — as a copy or link
• For mod­i­fied files, indi­cate in a con­spic­u­ous place that they have been mod­i­fied
• Orig­i­nal copy­right, patent, trade­mark and copy­right notices may not be removed.
• If the orig­i­nal soft­ware con­tains a “NOTICE” text file, the copy­right notices from the file must be repro­duced exactly as indi­cated

GPLv3/MIT/Apache 2.0 compatibility with each other

GPLv3/Apache 2.0: Source code under Apache 2.0 can be used in a GPLv3 project because Apache 2.0 con­tains fewer con­di­tions than GPLv3. There is no com­pat­i­bil­ity the other way round or with other ver­sions (e.g. GPLv2). Apache 2.0 con­tains a pro­vi­sion accord­ing to which patent rights may be revoked under cer­tain con­di­tions. This con­tra­dicts GPLv2.

GPLv3/MIT: Due to the few restric­tions, MIT source code can be used in GPLv3 projects with­out any prob­lems. The reverse is not pos­si­ble.

Apache 2.0/MIT: com­pat­i­ble

GPLv3 com­pat­i­ble also with:

- BSD License with­out adver­tis­ing clause,
- Affero Gen­eral Pub­lic License, Ver­sion 3 (see Sec­tion 13 of GPLv3)
- Lesser Gen­eral Pub­lic License, Ver­sions 2, 2.1 and 3 (LGPL)
- CeCILL (CONTRAT DE LICENCE DE LOGICIEL LIBRE CeCILL)
- Artis­tic License 2.0
- Zope Pub­lic License, Ver­sion 2.0 and 2.1