libpng License

Also known as Libpng, libpng License.

Commercial use: allowed
Share alike: not required
Attribution: required (keep the copyright and license notices)

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Write this as a license text (needs an account) DALICC reads the model above and writes what it permits, requires and prohibits in plain English. Without an account, the Text download above writes the model out from the vocabulary.

Canonical URI https://dalicc.net/licenselibrary/Libpng

Permissions

Change license by library convention
Duties
- Use a compliant license by library convention
Charge distribution fee from the text
Commercial use from the text
Derivative works from the text
Derive from the text
Duties
- Modification notice from the text
- Notice from the text
- Rename from the text
Display from the text
Distribute from the text
Duties
- Notice from the text
Modified works from the text
Modify from the text
Duties
- Modification notice from the text
- Notice from the text
- Rename from the text
Present from the text
Reproduce from the text

Prohibitions

This license states no prohibitions.

License-wide duties

This license states no duties that apply to the work as a whole.

What applies by default

The statements above are the library's reading of this license: each is marked with the sentence it rests on, or as a library convention where the text is not explicit. The statements below are the ones the DALICC reasoner supplies for acts the license says nothing about, from the default rules of the dependency graph it reasons with. Each one names the legal source it rests on. None of it is in the record.

Promote by default rule (adopted)

This license says nothing about Promote, and the graph applies this reading in all jurisdictions it covers: it is not permitted unless the license permits it.

A licence that says nothing about endorsement is read as not allowing it: the licence gives the licensee no right to use the licensor's name or marks in a way that states or implies that the licensor endorses the licensee or its product, while stating truthfully that a work is based on or uses the licensed work is a different act that this rule does not decide. A copyright licence grants rights in the work, and the right to use a name or a trademark is a separate right under trademark law and the protection of names, which a silent copyright licence does not pass on. Combining a licence that is silent about endorsement with one that permits it shows a conflict marked as coming from this rule.

Basis Trademark and name rights are separate from copyright: Regulation (EU) 2017/1001 article 9 lets the proprietor of an EU trade mark prevent all third parties not having his consent from using the sign in the course of trade, and Directive (EU) 2015/2436 article 10, 15 U.S.C. 1114 and 1125(a), section 12 BGB and section 43 ABGB protect marks and names in the same way. The library's evidence is Creative Commons 4.0 section 2(b)(2): Patent and trademark rights are not licensed under this Public License. A copyright licence that is silent grants no right to use the licensor's name or marks to suggest endorsement (Worldwide)

Clauses

Warranty disclaimer

The PNG Reference Library is supplied "AS IS". The Contributing Authors and Group 42, Inc. disclaim all warranties, expressed or implied, including, without limitation, the warranties of merchantability and of fitness for any purpose.

Limitation of liability

The Contributing Authors and Group 42, Inc. assume no liability for direct, indirect, incidental, special, exemplary, or consequential damages, which may result from the use of the PNG Reference Library, even if advised of the possibility of such damage.

Additional clauses

There is no warranty against interference with your enjoyment of the library or against infringement. There is no warranty that our efforts or the library will fulfill any of your particular purposes or needs. This library is provided with all faults, and the entire risk of satisfactory quality, performance, accuracy, and effort is with the user.

Info

Target asset types: Software
Region / jurisdiction: Worldwide
Validity: Perpetual
Source: https://spdx.org/licenses/Libpng.html
Legal code: https://spdx.org/licenses/Libpng.html
This description is published under: Creative Commons Attribution 4.0 International
SPDX identifier: Libpng on the SPDX license list
DALICC identifier: Libpng

This record is published under CC BY 4.0. Credit it as: DALICC License Library, DALICC - Verein zur Förderung der Rechtssicherheit in der Datenbewirtschaftung, https://dalicc.net, CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). The license it describes belongs to its publisher.

Use this license

Everything below is generated from this record. Replace the example address with the address of your own work.

JSON sidecar

{
  "license-uri": "https://dalicc.net/licenselibrary/Libpng",
  "license-title": "libpng License",
  "spdx-id": "Libpng",
  "asset": null,
  "generated-by": "DALICC"
}

RDF, Turtle

@prefix cc: <http://creativecommons.org/ns#> .

<https://example.org/my-work>
    cc:license <https://dalicc.net/licenselibrary/Libpng> .

RDF, JSON-LD

{
  "@context": {
    "cc": "http://creativecommons.org/ns#"
  },
  "@id": "https://example.org/my-work",
  "cc:license": {
    "@id": "https://dalicc.net/licenselibrary/Libpng"
  }
}

This license carries no attribution duty, so no credit line is offered here.

Badge

Markdown

[![License: libpng License](https://dalicc.net/license-library/Libpng/badge.svg)](https://dalicc.net/license-library/Libpng)

HTML

<a href="https://dalicc.net/license-library/Libpng"><img src="https://dalicc.net/license-library/Libpng/badge.svg" alt="License: libpng License"></a>

Review

Written from the license text by: Giray Havur
Written on: 2026-09-22
Second review: not yet done
Record changed since this review: yes (version 2, 2026-09-24)
Findings: 12 recorded, 8 applied to the record, 0 proposed

Models the libpng notice as it stood for versions 1.2.6 to 1.4.5, which is the text SPDX lists under this identifier. The operative part is three restrictions in the zlib shape: do not misrepresent the origin, mark altered versions, and leave the copyright notice alone. The record follows TheZlibLibpngLicense.

12 findings

info Rubric 1 spdx:licenseId applied

File name, record identifier, SPDX identifier and IRI local name are all Libpng. The library already holds the zlib text under the descriptive identifier TheZlibLibpngLicense with spdx:licenseId Zlib, and that record carries "Libpng" as a dct:alternative; the two are different texts and different SPDX identifiers.
info Rubric 2 odrl:target applied

One odrl:AssetCollection of dct:type dcmitype:Software.
major Rubric 3 odrl:permission applied

The grant reads "Permission is hereby granted to use, copy, modify, and distribute this source code, or portions hereof, for any purpose, without fee, subject to the following restrictions". The record permits reproduce, distribute, modify, derive, display, present, derivative works, modified works and the distribution fee. cc:CommercialUse rests on the separate sentence "The Contributing Authors and Group 42, Inc. specifically permit, without fee, and encourage the use of this source code as a component to supporting the PNG file format in commercial products".
major Rubric 3 odrl:permission applied

dalicc:ChangeLicense is permitted with the dalicc:compliantLicense duty. Nothing in the text bars a change of terms, and the notice condition has to survive one.
minor Rubric 4 odrl:prohibition none

No prohibitions. The text has no endorsement or trademark clause. The sentence about the PNG logo files is a statement about what ships with the library, not a restriction.
major Rubric 5 odrl:duty applied

cc:Notice hangs off odrl:distribute, odrl:modify and odrl:derive for restriction 3, "This Copyright notice may not be removed or altered from any source or altered source distribution". dalicc:modificationNotice and dalicc:rename hang off odrl:modify and odrl:derive for restriction 2, "Altered versions must be plainly marked as such and must not be misrepresented as being the original source".
minor Rubric 5 odrl:duty applied

No cc:Attribution. The text says "If you use this source code in a product, acknowledgment is not required but would be appreciated", so there is no credit duty, which is the same reading TheZlibLibpngLicense gives.
minor Rubric 6 dalicc:WarrantyDisclaimer applied

The disclaimer paragraph carries the warranty sentences and the liability sentence and is split at the sentence boundary. The additions to the disclaimer that the text attaches to versions 1.0.7 through 1.2.5 are quoted in dalicc:additionalClauses rather than merged into the disclaimer, because they apply to a named range of versions. The quoted clauses come from a text that wraps lines and uses two spaces after a full stop. Line breaks and repeated spaces are collapsed to a single space, which is how every other record in the library quotes a multi-line clause. No word and no punctuation mark is changed.
info Rubric 7 cc:jurisdiction applied

The text names no legal system and sets no term, so cc:jurisdiction is dalicc:worldwide and dalicc:validityType is dalicc:perpetual.
info Rubric 8 dalicc:additionalClauses none

No clause of this text needs a term the vocabulary does not have. The per-version copyright roll and the list of contributing authors are provenance rather than terms and are not quoted.
info Rubric 9 record none

The consistency check of app.services.composer against the dependency graph dg_default returned an empty conflict list.
info Rubric 10 record none

Read against licensedata/licenses/TheZlibLibpngLicense.ttl the duty set is identical. The difference is in the clause texts and in the express sentence about commercial products, which this text has and the zlib text states inside its grant instead.

Report an issue The review record as JSON The review checks the model against the license text. It is not legal advice.

History

This license model has 2 versions. Version 2 is the one served today; every earlier version keeps its own address, so a conclusion drawn from one of them can still be checked against it.

Version 2 current2026-09-24 Giray Havur

The changes since version 1 recorded which sentence of the text each statement rests on and named the license the record itself is published under.

View version 2 JSON-LD Turtle RDF/XML
3 changes
- changed permission cc:CommercialUse
  
  was permission cc:CommercialUse
  
  Manual edit The statement now quotes the sentence of the licence text it rests on: "The Contributing Authors and Group 42, Inc. specifically permit, without fee, and encourage the use of this source code as a component to supporting the PNG file format in commercial products."
- changed permission dalicc:ChangeLicense with duties [dalicc:compliantLicense]
  
  was permission dalicc:ChangeLicense with duties [dalicc:compliantLicense]
  
  Manual edit The statement is marked as a library convention, family rule 15: Permissive records permit relicensing: the text does not state it in as many words. Its duty dalicc:compliantLicense is marked as a library convention, family rule 15: Permissive records permit relicensing.
- added dct:license <https://creativecommons.org/licenses/by/4.0/>
  
  Manual edit Every record is published under CC BY 4.0. cc:license names the record DALICC keeps of that licence; dct:license now names it by the address Creative Commons publishes it at, so that a consumer matching the canonical IRI finds it.
Version 1

Created from the license text on 2026-09-22 (Permissive variants).

View version 1 JSON-LD Turtle RDF/XML

Every change names the reason behind it: a finding of the content review, one of its library-wide decisions, the metadata that review wrote onto every record, or a hand edit. None of it is legal advice.

Nothing on this page is legal advice. What a license means is decided by its text; ask a legal advisor before you rely on it.