Generate and sign Thai-ETA legal contracts

What ETA 2544 actually requires

Thailand's Electronic Transactions Act B.E. 2544 (Sections 9-11) gives electronic signatures the same legal standing as wet-ink signatures, provided three conditions are met:

1. Signer identity — the signer must be reliably identifiable (Thai national ID upload, foreign passport, or company TIN + registered representative).
2. Integrity — the signed document must be tamper-evident (hash + timestamp).
3. Method appropriate to the transaction — higher-value contracts require stronger signer verification.

DevProp's e-signature engine ticks all three by default. The audit trail it produces (PDF/A export + JSON event log) has been accepted as evidence in Thai courts in multiple precedent cases (Sansiri 2024 settlement is the most-cited).

Contract templates included

On every plan, you get the standard Thai-market templates in EN + TH (toggle per contract):

1. Reservation agreement (สัญญาจอง) — 1-2 page short-form, typical reservation fee deposit
2. Sale and purchase agreement (สัญญาซื้อขาย) — full SPA, customizable clauses
3. Residential lease (สัญญาเช่าที่อยู่อาศัย) — Thai Civil Code §537-571 compliant
4. Commercial lease (สัญญาเช่าพาณิชย์) — 3-year standard with renewal options
5. Land office side agreement (สัญญาเสริมด้านกรมที่ดิน) — separate from the public deed, captures pricing and payment terms

On Professional / Custom plans, you can upload your agency's own template DOCX, our engine extracts the merge fields and converts it to a DevProp-managed template (~5 min one-time setup per template).

Step 1 — Generate the contract

From the deal record (Pipeline → Stage "Contract"), click Generate contract. Three picks:

1. Template (Reservation, SPA, Lease, etc.)
2. Language (EN or TH — both sides see the same content in their preferred language)
3. Parties (auto-populated from the lead record + listing)

Click Generate. The engine merges all fields, renders to PDF/A (the archive-quality variant required by Thai courts), and shows you the preview. Edit any field inline before sending (the merge fields go red if invalid).

Step 2 — Add signers

Default signers based on contract type:

1. Reservation: Buyer + Agency representative (2 signers)
2. SPA: Buyer + Seller + Agency + (optional) Buyer's lawyer + Seller's lawyer (up to 5)
3. Lease: Tenant + Landlord + (optional) Agency as witness (3)

For each signer, you set:

1. Full legal name (Thai script for Thai persons, Latin for foreigners)
2. ID method — Thai national ID, foreign passport, or company TIN
3. Email + phone (the signing link goes to both; signer can pick)
4. Order — sequential signing (signer 1 must complete before signer 2 gets the link) or parallel (all get links simultaneously)

Step 3 — Send for signature

Click Send. Each signer receives:

1. An email with a unique signing link (expires in 7 days, configurable)
2. An SMS notification with the same link (Thai mobile numbers only)
3. A LINE notification if the signer has a LINE OA conversation linked to this deal

Clicking the link takes them to the signing page (mobile-optimized, no app install required). They:

1. Confirm their identity (upload Thai ID photo, or scan their passport with their phone)
2. Read the contract scrolled top-to-bottom (the system tracks scroll depth — a partially-read contract is flagged)
3. Type their name + signature (or draw it with a stylus / finger)
4. Tap Sign and submit

The system locks the document the moment the last signer completes. You can't modify a signed contract — only generate a new version + send for re-signature.

Step 4 — Audit trail

After signing, the contract record contains:

1. PDF/A of the signed document (universally readable, ISO 19005 archive standard)
2. JSON event log: every action with timestamp, IP, user agent, geolocation (when permitted by signer)
3. Cryptographic hash of the original + each subsequent version (proves integrity)
4. Identity verification artifacts (ID photo, signature image, OTP/SMS confirmation)
5. Certified PDF receipt for each signer (their copy of the audit log)

All of this is admissible as evidence under Thai Civil and Commercial Code §93, §123 and the ETA Act §9-11.

Withdrawal and amendments

A signer can withdraw before signing by clicking the withdrawal link in their email. This invalidates only their pending signature — other signers' completed signatures remain valid. You can then send a new version.

After all signatures, the contract is final. To amend, generate a new contract version with an amendment clause that references the original. The original stays in the archive; the amendment is signed by all parties.

Bulk-sending (developer-direct workflow)

For developer-direct agencies handling 30+ similar SPAs in a launch month: Contracts → Bulk send. Upload a CSV with one row per (deal, signer) and the system generates + sends all contracts in one operation. Each follows the same audit trail rules; reporting on bulk batches is grouped by upload reference.