Trust & Security centre
Built like financial infrastructure.
Off-market property deals run on trust between strangers. Bidline replaces verbal assurances with cryptographic records, server-enforced privacy, and an audit trail a regulator can read. Every claim on this page describes a control that is implemented and running today — not a roadmap item.
The four pillars
Trust is engineered, not promised.
Tamper-evident records
Every bid is SHA-256 hash-chained to the one before it. Alter any record — even one character — and the chain breaks visibly. Retained to meet Australian record-keeping obligations.
Identity protection
Bidders compete as numbered paddles. Real identity is revealed to the listing agent only when a bid is accepted — never before, never to other bidders.
Finance privacy
Agents see a banded pre-approval tier and an expiry date. They never see your lender, your exact approved amount, or a single bank statement.
Server-side gating
Addresses, photos, and documents are withheld at the API. Nothing sensitive is sent to a browser and hidden with styling — if you're not entitled to it, it never leaves our servers.
Tamper-evident bid log
Every round is a chain. Break one link and everyone knows.
When a round opens, it is seeded with a unique genesis hash. Every bid that follows is hashed with SHA-256 and bound to the hash of the previous bid. The result is a chain in which no bid can be edited, reordered, backdated, or deleted without breaking every link after it.
Bid #6 · Paddle #2
prev: 9f3a…c21e
this: 4b78…aa02
SHA-256 sealed
Bid #7 · Paddle #4
prev: 4b78…aa02
this: d1c5…07f9
SHA-256 sealed
Bid #8 · Paddle #2
prev: d1c5…07f9
this: 82ee…b340
SHA-256 sealed
Each bid's record includes the hash of the previous bid. Tampering with bid #7 changes its hash — and bid #8 no longer matches, exposing the alteration instantly.
The integrity pack
Sellers and administrators — nobody else — can pull a per-round integrity pack. It re-verifies the bid chain from the genesis hash to the final bid, link by link, and lists the round's logged audit events beside it: the open, counters, declines, acceptances, timer extensions, cancellations, and admin actions. On a sealed round the pack is held back until the round closes, so it cannot be used as a side door into a field that is still hidden. If anyone ever questions how a round was run, the answer is a verifiable document, not a recollection.
Disclosure versioning
Every audited action records the exact version of the compliance disclosures the actor saw at that moment. There is never a question of "what did the bidder agree to?" — the record says precisely which wording was on screen when they acted. All of it is retained to meet Australian record-keeping obligations.
Privacy by design
Everyone sees exactly what they need. Nothing more.
Paddle-masked bidders
Paddle #4In every round, bidders appear as numbered paddles — to the agent and to each other. Your real identity is revealed to the listing agent only if your bid is accepted. Competing bidders never learn who you are.
Address masking
Suburb onlyThe exact street address is withheld from everyone except the listing agent and the accepted bidder. Listings show suburb-level location. Photos and video are never returned to anonymous visitors at all.
Banded finance tiers
Tier B · exp 14 AugYour pre-approval is reviewed manually by our team. Agents then see only a banded tier and its expiry date — never your lender, never the exact approved figure, never your bank statements. Enough to trust the bid; nothing to negotiate against.
Encrypted PII
AES-256-GCM · AWS KMSStreet addresses, client addresses, and phone numbers are encrypted at rest with AES-256-GCM envelope encryption under AWS KMS. They are decrypted only at authorised API boundaries — a database read alone reveals nothing.
Gating happens on the server
Many sites "hide" sensitive data with CSS while still sending it to your browser. Bidline does not. Access checks run server-side on every request: AWS Cognito identity, 12+ character passwords, and a server-verified JWT on each call. Verification and ban status are re-checked on every single bid — a suspended user cannot keep bidding on a stale token.
Compliance posture
Aligned with the strictest rules in the country.
Bidline builds NSW-grade discipline into every listing nationwide — because the strictest standard is the right default.
Underquoting-aligned price guides
Every indicative price range must sit within the agency's own estimate, with the top of the range capped at 110% of the bottom. Structured price-guide discipline is enforced by the platform, not left to habit.
Banned-phrase checks
Listing copy is automatically screened for the phrases regulators prohibit in price marketing. Non-compliant language is caught before a listing goes live.
Manual verification, 24-hour SLA
Agent licences are checked against state registers by a human. Buyer pre-approvals are reviewed manually. Every application is reviewed within 24 hours — no self-attestation, no automated rubber stamp.
Disclosure versioning on every action
Each bid, counter, acceptance, and decline records the exact compliance-disclosure version shown to the actor at that moment, permanently bound into the audit trail.
Infrastructure
Australian data, bank-grade plumbing.
Region
AWS Sydney
ap-southeast-2
Core platform records are stored and processed in Australia.
Datastores
Aurora PostgreSQL + DynamoDB
Encrypted at rest
Relational records and high-volume event data, both encrypted at rest.
Bid integrity
SHA-256 hash chain
Genesis → final bid
Each bid is bound to the hash of the bid before it. The per-round integrity check recomputes every link and names the first one that does not match.
In transit
TLS everywhere
CloudFront
All traffic is encrypted in transit via CloudFront with TLS. No plaintext paths.
Plain dealing
What Bidline is not.
Bidline Pty Ltd (ACN 698 484 847) is a technology marketplace. Being precise about what we don't do is part of how we earn trust:
Not an agent or auctioneer
We don't represent vendors or buyers, we don't conduct auctions, and we don't hold a stake in any transaction. Licensed agents run their deals; Bidline provides the structure and the record.
Bids are non-binding
A bid on Bidline is a serious, finance-verified expression of intent — but it is not a contract. Contracts are negotiated and executed off-platform by the parties' own lawyers and conveyancers, under the laws of the relevant state or territory.
Never an escrow
Bidline never touches settlement funds. No deposits, no trust accounts, no payment rails between buyer and seller. Money moves between the parties' legal representatives exactly as it does in any conventional sale.
Full terms in our terms of service and privacy policy.
Trust you can verify, not just believe.
Join the founding members and run your next off-market round on infrastructure built for scrutiny.