Detection-as-Code for Fraud

Fraud detection
that writes itself.

Combine signals across the data sources you already have. 10-50x fewer false positives. Audit-defensible by design. Filing-grade end to end.

atrosa-detections · production hunt #114

24h7d30dQuarter

Last 24h · 11:08 UTC

3 detections active
{}

cross_source_temporal_correlation

Fired on 4 users. Evidence chain attached.

Velocity × KYC × Device

fired
{}

peer_baseline_amount_anomaly

12 alerts. 11 confirmed in replay. 1 pending review.

Peer-group MAD-z

review
{}

mule_account_velocity

Authored 12:42 UTC. Shadow Run on 90d backtest.

Graph + temporal

shadow
False positive rate vs baseline−37×

Alerts after de-noising · this week

142 alerts

5,420 events scanned · 37× fewer FPs

Detections audited end-to-end

MonTueWedThuFriSatSun

See it work

From noise to precision. Autonomous.

Active Data Sources

Gateway Logs
Device Telemetry
Event Stream
Core Records

Agent Output

detect.py

Iteration

0

False Positives

-

SNR Score

0%

Pick your fraud pain

Which one is
eating your week?

001Solved

“My rule fires 50 false positives a day.”

False-positive triage

  • Multi-source DaC authoring
  • Peer-baseline MAD-z
  • Evidence chain on every alert
  • 10-50× FP reduction

atrosa-detections · cross_source_temporal_correlation

002v0.2

“My vendor locked me out at renewal.”

Vendor lock-in

  • Code in your repo
  • Mirror to your GitHub
  • Portable Python, no DSL handcuffs
  • Vendor can't gate it

MIT-licensed substrate · `atrosa-cli` v0.2

003Solved

“Backtest produces results, not audit-grade evidence.”

Audit asymmetry

  • Same artifact backtest + live
  • Code review = audit trail
  • Replay simulator
  • MRM-pack auto-derivable

Confirmed wedge · Sift + Unit21 demos 2026-05-27

004v0.2

“My analysts hand-assemble cases for hours.”

Manual glue work

  • Cross-system evidence assembly
  • Pull from your existing tools
  • Automated case context
  • Workflow-shaped UX

Data connectors · case-mgmt stack-mate

005M7 roadmap

“SAR write-ups take 2 hours each.”

Filing burden

  • Five-Ws narrative generation
  • Typology citation from FinCEN library
  • Defect-checker (FFIEC Appendix L)
  • BSA E-Filing XML output

M7 filing-package generator · 6-10 wks to v0

006

Pain you haven't named

The roadmap is iterative. Tell us where analyst hours are bleeding and we'll author a detection family for it.

Suggest a pain →

How ATROSA works

Four steps. One agent owns the loop.

01 · Pull

Connect your data sources.

Stripe, Datadog, KYC providers, warehouse. ATROSA reads from where your data already lives. No event ingestion API, no SDK.

02 · Author

AI writes the detection.

An iterative loop hunts patterns across sources, composes detections as Python, tests them against your history before they go live.

03 · Investigate

Evidence chains assembled automatically.

Every alert lands with its receipts. Which sources fired, which thresholds, which peer baselines. Analysts review a package, not a score.

04 · File

Filing-grade packages, MLRO-ready.

Five-Ws narrative, typology citation, FFIEC defect-checker pass, BSA E-Filing XML. MLRO reviews and submits. AI does the assembly.

How ATROSA is different

Others bolt AI onto pre-agentic stacks. ATROSA is for the post-agentic native investigators.

Sift, Unit21, Hummingbird ship AI-assist on top of legacy workflow. ATROSA owns the loop: writes detection, runs investigation, emits the filing package.

vs. Sift / Sardine

Pre-Cursor copilot

AI suggests rules in a no-code UI. You approve. Artifact lives in their database as DSL.

ATROSA

AI authors DaC on your data. Artifact is Python in your repo. Audit reads like git blame.

vs. Unit21

Pre-Cursor copilot

AI rule recommendations from labeled history. Templates someone else's fraud team validated.

ATROSA

Cold-start without labels. DaC written for YOUR data on day one. 24h Shadow Run.

vs. Hummingbird / Lundy

Pre-Cursor copilot

Polishes the SAR UI. The investigation work itself doesn't get faster.

ATROSA

Filing-grade package end-to-end. Evidence cited from source. Defect-checker pass before MLRO review.

The agent

Meet the driver. Not the copilot.

ATROSA owns the loop. Writes the detection, runs the investigation, drafts the filing. Your team reviews and approves what matters.

  • Writes detections from your data

    Hunts patterns across sources. Composes Python detections combining velocity, peer-baselines, and cross-source signals.

  • Tests before it ships

    Every authored detection runs against your history first. FP rates, recall, evidence-chain coverage. All measured before deploy.

  • Builds the case file itself

    Pulls account history, transaction patterns, prior cases. Your analyst opens a package, not a score.

  • Drafts the filing, defect-checked

    Five-Ws narrative, typology citation, FFIEC defect pass. MLRO reviews and submits. Assembly is autonomous. Accountability stays human.

detect_mule_velocity.pyauthored by AI
# cross-source velocity detection
def detect_mule_velocity(df):
    z = mad_z_score(
        df, "outbound_amount",
        peer_key="cohort",
    )
    velocity = peer_group_baseline(
        df, "txn_per_hour",
    )
    signal = (z > 3.5) & (
        velocity.ratio > 2.4
    )
    return build_evidence_chain(
        df[signal], "mule_velocity_v3",
    )
replay · 90d · 14 alerts · 13 confirmedFP rate −42×
Live · audit-ready

Pricing

Scales to your full fraud surface.

Open Source

Free

Run the detection library on your own infra. Engineer-led adoption.

Star on GitHub
  • atrosa-detections public repo
  • Python helpers (MAD-z, peer baselines, evidence chains)
  • Flagship detections + replay fixtures
  • MIT license, no usage caps
For early and mid-market

Self-serve

$5-25K/year

Seed-to-Series-A fintechs. AI-authored detections on YOUR data, hosted.

Request access
  • AI iterative loop authoring detections from raw data
  • Shadow Run: 24h to first detection
  • Data connectors (Stripe, Datadog, KYC, warehouse)
  • Replay simulator + audit timeline
  • Slack-native alert delivery

Detection Platform

$50-500K/year

Series A+ fintechs with engineering-led fraud teams.

Talk to founder
  • Everything in Self-serve
  • Multi-source autonomous composition
  • MRM-pack auto-generation
  • Filing-package generator (M7), coming
  • Co-deployed with existing case-mgmt stack
  • Mirror detections to your git repo

Pricing is hybrid base + usage. Enterprise tier ($500K-$5M) available for multi-region / multi-team. SOC 2 + DPA on the roadmap.

Questions fraud teams ask

Frequently asked. Honestly answered.

DaC, Shadow Run, regulator trust. The questions fraud teams open with.

What is Detection-as-Code (DaC), exactly?

Detection logic lives as version-controlled Python in a repo, not as DSL in a vendor database. Same pattern Panther brought to SecOps. Your team reads the rule that fired, replays it on history, audits it like any code change. ATROSA's iterative loop authors that code from your raw data.

How is this different from Sift / Unit21 / Sardine?

Those vendors ship AI that suggests rules in a no-code UI; the artifact lives in their database. ATROSA writes the DaC itself; the artifact is Python in your repo. They are pre-Cursor copilots, AI bolted onto a rule builder. ATROSA is the driver. The AI is the authoring layer.

How does Shadow Run work?

We connect to your data sources read-only, replay 90 days of history through ATROSA's iterative loop, and produce a side-by-side. Which of your existing alerts ATROSA would have caught. Which it dismisses as false positives. What new patterns it surfaces. You see the FP-reduction number on YOUR data before you sign anything. 24h to first detection.

Can the regulator trust AI-authored DaC?

The rule is code, not a black-box score. Every parameter, threshold, source, and peer-baseline is inspectable. The replay simulator produces the same audit artifact in Shadow Run and production. Code review becomes the audit trail. For filing: the MLRO reviews and submits. Assembly is autonomous, accountability stays human, per FinCEN's October 2025 guidance.

What data sources do you support?

Pull-only via data connectors. Stripe and Datadog are standard. KYC providers (Persona, Sumsub, Onfido), Snowflake / BigQuery / Postgres warehouses, Mixpanel / Segment behavioral. No event ingestion API, no SDK. We read from where your data already lives.

What happens when an AI-authored rule misfires?

Every rule ships with replay receipts. We already know its historical false-positive rate before it deploys. If it misfires in production, you roll back like any code change. The evidence chain on each alert shows exactly which condition triggered. You edit the rule directly or hand it back to the loop with the new disposition labels.

How long does deployment actually take?

Shadow Run produces a first detection within 24h of connecting your data sources. Full production deployment, including SOC 2 / DPA review and human approval gates, typically lands inside 2-4 weeks for self-serve. Longer for enterprise, depending on procurement.

What about SOC 2, DPA, PII handling?

SOC 2 Type II and DPA are on the roadmap. For Shadow Run, a PII sanitizer runs at the connector layer. Detections operate on anonymized signals while you evaluate. In production, post-DPA, full PII is available for case-file assembly. Audit logs cover both modes.

Shadow Run in 24h

See your false positives drop before you sign anything.

Pull from your data sources. Run ATROSA's iterative loop on a 90-day backtest. Walk away with the FP-reduction number and the evidence chain. Even if you never become a customer.

Early access

Get on the waitlist.

ATROSA's autonomous detection platform is in private beta. Design partners get hands-on Shadow Run pilots. 24h to first detection on six months of your data, with regulator-grade audit.

View on GitHub

Or fork the open-source detection library and start now. No access required.