Copyright in software written by an outside developer is, under section 10 of Thailand's Copyright Act, owned by the client who commissioned it unless the parties agreed otherwise. Employee work under section 9 is the opposite: it belongs to the employee unless agreed in writing. This guide is for founders, CTOs and legal teams commissioning apps or systems.
- Section 4 of the Copyright Act treats computer programs as literary works, so source code is protected like writing.
- For commissioned work, section 10 vests copyright in the client unless the author and client agreed otherwise.
- For employee work, section 9 vests copyright in the employee unless otherwise agreed in writing.
- Under section 17, an assignment that does not state a duration is deemed to last ten years.
- A licence to you does not stop the owner licensing others unless the written licence prohibits it (section 16).
A company hires a freelancer or a software house to build an app, a back-office system or a website, pays in full, receives the files and assumes the software is now its own. The question of who really owns it tends to surface at the worst moment: when switching maintenance providers, during an investor's due diligence, or on discovering the developer has sold a near-identical system to a competitor.
Thailand's Copyright Act B.E. 2537 (1994) answers the question, but not the way many people assume. The answer depends on who wrote the code, in what capacity, and what the contract says. Below we go layer by layer through the text, and say plainly where the text does not give an answer.
Work produced with AI raises a separate question, covered in Who owns work made with AI under Thai copyright law?
What kind of copyright work is software?
Thai law places computer programs within literary works, protected the same way as writing. The definition in section 4 is wide enough to cover any programming language.
“computer program” means instructions, set of instructions or any other things, which are used with a computer so as to operate the computer or to generate an output, whichever the computer language is;
“literary work” means any kind of literary work such as books, pamphlets, writings, printed matters, lectures, sermons, addresses, speeches, including computer programs;
The consequence: the copyright owner has the exclusive rights under section 15 to reproduce, adapt, communicate to the public and license. Anyone who copies or modifies the code without permission infringes under section 30. Knowing who owns the code therefore decides who may keep developing the system and who may resell it.
Any of the following acts against a computer program copyrightable by virtue of this Act without authorization in accordance with section 15 (5) shall be deemed an infringement of copyright: (1) reproduction or adaptation,
You hired an outside developer. Who owns the copyright?
Unless the parties agreed otherwise, the client that commissioned the work owns the copyright under section 10.
Copyright in the work created in the course of commission vests in the employer unless the author and the employer have agreed otherwise.
In this translation "employer" means the person who commissioned the work. That sounds good for clients, but two things need checking. First, the end of section 10 allows the parties to agree otherwise. A software house's contract or terms of service may already say the developer owns the code and the client gets only a licence. Sign those terms and the exception applies at once.
Second, section 10 does not say that the contrary agreement must be in writing, unlike section 9, which does. Wording in an email or a quotation might be put forward as that agreement. The safer course is to deal with copyright in a single contract that states it replaces all earlier understandings.
Why doesn't a company automatically own code its own staff write?
Because section 9 sets the opposite default. Copyright in work created in the course of employment vests in the employee unless otherwise agreed in writing. The employer only gets the right to communicate the work to the public in line with the purpose of the employment.
Copyright in the work created by the author in the course of employment vests in the author unless it has been otherwise agreed in writing, provided that the employer is entitled to communicate such work to the public in accordance with the purpose of the employment.
Many companies believe outsourcing is riskier than building in-house. On the statutory defaults alone, the reverse is true: without an agreement, commissioned work goes to the client while employee work stays with the employee. Companies whose employment contracts say nothing about copyright should fix that first; see the guide on copyright in employee work.
| Who wrote the code | Section | Copyright vests in | What can change the result |
|---|---|---|---|
| Your own employee | Section 9 | The employee (the employer may publish it for the purpose of the employment) | Agreement in writing |
| A freelancer or firm you commissioned | Section 10 | The commissioning client | Any contrary agreement (no form prescribed) |
| A developer adapting code someone already owns | Section 11 with section 13 | The adapter, for the adaptation, without prejudice to the original owner | Sections 9 and 10 apply mutatis mutandis |
| Work commissioned or ordered by a government agency | Section 14 | The government agency | Agreement in writing |
When a software house's staff write the code, where can the chain of rights break?
Here the text gives no direct answer, so extra care is needed. Suppose you hire Company A to build a system. The people actually writing the code are Company A's employees, not Company A itself.
Between those employees and Company A, section 9 applies: unless Company A has a written agreement with them, copyright may sit with the employees. Between Company A and you, section 10 applies, and it speaks of the "author" and the "employer". Under section 4, the author is the person who actually makes the work.
“author” means a person who makes or creates any work, which is a copyright work by virtue of this Act;
How the two sections fit together when a company sits in the middle is not stated in the texts in our library, and we found no judgment or ruling in the library that resolves it. Do not assume you hold every right.
Who owns the developer's existing code, libraries and open source?
Almost no commissioned system is written from scratch. Developers bring code they reuse for every client and pull in other people's libraries. Section 11 gives the adapter copyright in the adaptation, but without prejudice to the owner of the original work.
Copyright in the work which is an adaptation of a copyright work by virtue of this Act done with the consent of the owner of copyright vests in the person who makes such adaptation but without prejudice to the owner of copyright in the work, created by the original author, which is adapted.
So even if the contract says you own everything, you cannot receive more than the developer has to give. The developer's reusable code remains the developer's; third-party libraries remain their owners' and are usable on their own licence terms. A good contract attaches a schedule separating new work, the developer's pre-existing code and third-party components.
If the developer keeps the copyright in its existing code and gives you only a licence, read section 16 as well.
The authorization by the owner of copyright by virtue of this Act to a person to exercise the right according to section 15 (5) shall not restrict the owner of copyright from granting such authorization to another person except when the restriction is specified in a written authorization.
Put simply: unless the written licence says otherwise, the developer can license the same code to your competitor. If the system is central to your business, state clearly that the licence is exclusive and within what scope.
The contract says "copyright is assigned". What should you watch for?
An assignment must be in writing, signed by both assignor and assignee, and should state its duration. If it does not, section 17 paragraph three deems it to last ten years.
The assignment of copyright by other means, except by inheritance, must be made in writing with signatures of the assignor and the assignee. If the duration is not specified in the assignment contract, the assignment shall be deemed to last for ten years.
The pattern to watch is a developer that keeps ownership under the exception in section 10 and then "assigns" it to the client on final payment. If that assignment states no term, your rights under it may lapse in year ten while the system is still running. Section 17 paragraph two allows assignment for the entire term of protection, so say so expressly.
The owner of copyright may assign the copyright in whole or in part and may assign it for a limited duration or for the entire term of copyright protection.
After you own the copyright, what rights does the author keep?
The author keeps the rights in section 18: to be identified as the author and to prevent the assignee from distorting or adapting the work in a way that damages the author's reputation or dignity, unless otherwise agreed in writing.
The author of a copyright work by virtue of this Act is entitled to identify himself as the author and to prohibit the assignee or any person from distorting, shortening, adapting or doing anything against the work to the extent that such act would cause damage to the reputation or dignity of the author. When the author has died, the heir of the author is entitled to litigation for the enforcement of his right through the term of copyright protection unless otherwise agreed in writing.
Software is modified throughout its life, so this should not be left open. Agree in writing that the author will not exercise section 18 rights against modifications the client needs to keep using the system.
How far do the section 35 exceptions help a business?
Less than people hope. Section 35 lists nine acts that do not infringe copyright in a computer program, including adapting it as necessary for use, but every one is conditional on the purpose not being for profit.
An act against a computer program which is a copyright work by virtue of this Act in the following cases shall not be deemed an infringement of copyright, provided that the purpose is not for profit and section 32 paragraph one is complied with:
A company running the system for its business may not meet that condition, so do not plan on section 35 to let you fix bugs or extend the system yourself. If you do not own the copyright, write the rights to modify, adapt and hire someone else for maintenance into the licence.
Source code you never received: what else protects it?
If the developer keeps the source code and delivers only the running program, owning the copyright on paper does not let you change the system. Source code may also be a trade secret, because the Trade Secrets Act B.E. 2545 (2002) counts programs as trade information.
“Trade information” means any medium that conveys the meaning of a statement, facts, or other information irrespective of its method and forms. It shall also include formulas, patterns, compilations or assembled works, programs, methods, techniques, or processes.
That cuts both ways. If you own the code, source code still held by the developer should be covered by a confidentiality agreement. If the developer owns it, it has no obligation to hand it over unless the contract requires it. Make delivery of source code and documentation part of every milestone; for drafting the confidentiality side, see An NDA That Actually Protects Your Trade Secrets.
Which clauses should a software development contract have?
Ordered from hardest to fix if forgotten, each tied to the sections quoted above.
- Copyright in new work vests in the client under section 10, with no other agreement reserving rights to the developer.
- If an assignment is needed, make it written, signed by both parties and for the entire term of copyright protection (section 17).
- A warranty that the developer holds written rights from every employee and subcontractor (section 9).
- A schedule of the developer's pre-existing code and third-party software with each licence (section 11).
- For pre-existing code the developer keeps, a licence to use, modify and have others maintain it, stating whether it is exclusive (sections 15 (5) and 16).
- A written agreement on section 18 rights for modifications needed for use.
- Delivery of source code, documentation and administrator access at every milestone.
- If the developer uses AI coding tools, disclosure and a warranty that the output does not infringe others' rights.
If the system will hold customer data, a developer that maintains it after delivery may also be a data processor under the PDPA; see Before You Sign a Vendor That Touches Customer Data.
Frequently asked questions
We paid in full but have no written contract. Who owns the copyright?
If the work was commissioned, section 10 vests copyright in the client unless the parties agreed otherwise. The hard part is proving it was a commission and that no other agreement exists, for example terms in a quotation. Gather evidence of the engagement and get a written confirmation of rights from the developer now.
Can the developer sell the system it built for us to someone else?
If you own the copyright under section 10, reproducing or adapting it without permission infringes under section 30. If the developer kept ownership and only licensed it to you, section 16 lets it license others unless the written licence prohibits that.
Is a long-term freelancer an employee or a contractor for copyright purposes?
The Copyright Act separates work done "in the course of employment" (section 9) from work done "in the course of commission" (section 10) but gives no test for telling them apart; the real relationship decides. Our library does not hold the labour-law text that would settle it, so always put copyright terms in writing either way.
Can we fix bugs or add features ourselves without the developer's permission?
If you do not own the copyright, unauthorised adaptation falls under section 30 (1). The exception in section 35 (8) for adapting a program as necessary for use requires a non-profit purpose, so secure a right to modify in the contract from the start.
Our copyright assignment states no duration. What should we do?
Section 17 paragraph three deems such an assignment to last ten years. If you need longer, sign a new written assignment, signed by both assignor and assignee, for the entire term of copyright protection.
Law and sources
- Copyright Act B.E. 2537 (1994) — Section 4 · 9 · 10 · 11 · 16 · 17 · 18 · 30 · 35
- Trade Secrets Act B.E. 2545 (2002) — Section 3
Text in the "The text" boxes is copied word for word from AIPDPA's legal knowledge base, transcribed from the Royal Gazette and official documents; every edit is checked by the system against that base, character by character. English wording is an unofficial translation; the Thai text prevails. This article is general information, not legal advice for a particular case.
Do it in the system
Who stands behind this guide?
Written by the AIPDPA legal team · Content owner: Phuwara Krobtaku, Attorney-at-law · Thai Barrister-at-Law · technology & intellectual property counsel
Lawyer's licence no. 477/2558 · Thai Barrister-at-Law · LL.M. in Intellectual Property & IT Law (Gold Medal)