What Mercury data does Well pull into Pennylane?

Mercury streams transactions, wires, ACH transfers, card payments, and counterparty records to Well over its MCP server. After Well resolves the counterparty and assigns a confidence score, the matched record posts to Pennylane as supplier and customer invoices via email-in, with amount, VAT, and date pre-filled by Pennylane's OCR, with the Mercury event ID preserved on the entry for audit.

What happens to historical Mercury data when I first connect to Pennylane?

Mercury exposes the last three years through its API on a connected account. The window Well actually pulls is configurable from the integration settings page; each record is matched against your existing Pennylane ledger, and re-running the backfill is safe because Well tracks the Mercury record IDs and updates existing Pennylane entries instead of duplicating them.

Does Well handle multi-currency records between Mercury and Pennylane?

Mercury reports a single base currency; Well stores the value verbatim and tags the record so your Pennylane ledger can apply its own conversion rule at posting time. Exchange-rate fields are not synthesised, so the Pennylane entry carries the unchanged Mercury amount and the conversion is owned by the Pennylane accounting policy.

How does Well prevent duplicates when posting Mercury records to Pennylane?

Mercury sends each event with a stable resource ID that Well tracks against the Pennylane ledger. Webhook replays (which Mercury can issue for delivery retries) are recognised by ID and either skipped or used to update the existing Pennylane entry. Distinct records that look similar are caught by Well before posting, with the candidates surfaced in the review queue when confidence is ambiguous.

What happens if a Mercury record fails to post to Pennylane?

When a record fails to post to Pennylane (validation rule, missing field, transient 5xx), Well retries automatically with backoff. Auth failures short-circuit the retry loop and notify the workspace owner; schema rejections are kept on the integration status page with a one-click retry-after-fix action pointing back at the original Mercury record. Nothing silently drops.

How does Well authenticate with Mercury and Pennylane?

Mercury's MCP server handles authorisation directly; Well receives an access token through Dynamic Client Registration and never sees raw user credentials. For the delivery side, Well forwards the reconciled document to your Pennylane email-in address once it clears the matching threshold; Pennylane creates the draft record from it and you confirm and post it. Well holds no write credential to Pennylane. Tokens are encrypted at rest and in transit under TLS 1.3. Pennylane hosts in the EU and Mercury hosts outside the EU; Well processes records per the storage region configured for your workspace.

Mercury to Pennylane

AvailableNative · MercuryNative · Pennylane

Connect Mercury to Pennylane with Well

Reconcile Mercury transactions and transfers against your open invoices inside Well, then forward the matched documents to Pennylane's email-in inbox for one-click review.

Connect both toolsView all integrations

Mercury

Source

The Mercury integration connects your startup banking to Well via MCP, pulling transactions, balances, and counterparty data into your workspace.

Pennylane

Target

The Pennylane integration creates a bidirectional bridge between Well and your accounting workspace.

Why this pair

Mercury runs in USD on US banking rails; Pennylane runs in EUR for French SMBs.

Connecting them through Well handles the currency conversion, the counterparty resolution, and the matching in one pass inside Well's own ledger. Well matches every Mercury transaction against your existing invoices with the FX rate of the booking date and the original Mercury reference preserved, then forwards the matched document to Pennylane's supplier or customer email-in address so Pennylane creates the invoice with the data pre-filled.

What Well does between Mercury and Pennylane

One-way: Mercury into Well into Pennylane
Sync mode: Real-time MCP push
Events arrive in seconds

Trigger from Mercury

6 events · pick one

Well engine·recipe·When a new transaction posts on your Mercury account

Source

from bank line · live webhook

OVH Cloud SAS

via Mercury

Transaction

When a new transaction posts on your Mercury account

INV-1024 · 22 Apr 2026$1,284.00

Extract

5 fields read from Mercury

5 fields read

CounterpartyOVH Cloud SAS
Booking date22 Apr 2026
Amount$1,284.00
CurrencyUSD
ReferenceINV-1024

Enrich

against your historical record graph

4 fields added

CounterpartyOVH Cloud SAS
Tax idFR22424761419
Ledger account6156 · IT hosting
Match1 candidate invoice

Confidence97%

<55% refused55–85% review≥85% auto-posts

Post

post as supplier and customer invoices

Create a supplier invoice in Pennylane

auto-posted

posted

TypeSupplier invoice
VendorOVH Cloud SAS
Amount$1,284.00
Ledger6156 · IT hosting
Source docattached
Confidence97%

audit linkto Pennylane

Action in Pennylane

1 compatible with this trigger

Create a supplier invoice in Pennylane

Reconcile Mercury transactions to Pennylane entries with EU residency intact.

01Featured

Reconcile transactions to existing invoices

Every Mercury debit is scored against your open invoices inside Well on counterparty, amount, scheduled date, and currency. Above the auto-link threshold the bank line is linked to the right invoice; the matched document is then forwarded to Pennylane's email-in inbox with the receipt attached for your one-click confirmation.

Categorise unmatched debits by counterparty

When a Mercury debit has no matching invoice in Well, the counterparty is checked against your prior history and a category is proposed. Approve the proposal once for a new vendor and Well applies it to every subsequent Mercury debit from the same counterparty before forwarding to Pennylane.

Pull statement balance for month-end close

At month-end Well snapshots the Mercury statement balance and surfaces every reconciling item in one queue inside Well. Outstanding cheques, in-transit deposits, and timing differences land on their own bucket so the controller clears the diff before forwarding matched documents to Pennylane.

Split card statement lines into per-employee context

Aggregated Mercury card statement lines from corporate cards are decomposed inside Well into per-employee, per-merchant documents. Each per-employee document is forwarded to Pennylane separately, so expense ownership stays attached to the underlying transaction in the target ledger.

13 signals and actions across Mercury and Pennylane

When a Mercury account is read
Pulls from the Mercury transactions API. Pulls each Mercury account the workspace holds with its balance, currency, and routing details. Forwarded to Pennylane's email-in with amount, VAT, and date pre-filled by Pennylane's OCR.
Trigger·Account
When a Mercury card charge posts
Pulls from the Mercury transactions API. Captures debit card transactions with merchant and MCC code. Forwarded to Pennylane's email-in with amount, VAT, and date pre-filled by Pennylane's OCR.
Trigger·Transaction
When a wire transfer is sent from Mercury
Pulls from the Mercury transactions API. Tracks outbound wires with beneficiary detail and instruction. Forwarded to Pennylane's email-in with amount, VAT, and date pre-filled by Pennylane's OCR.
Trigger·Transaction
When an ACH payment clears in Mercury
Pulls from the Mercury transactions API. Picks up cleared ACH credits and debits with the company id reference. Forwarded to Pennylane's email-in with amount, VAT, and date pre-filled by Pennylane's OCR.
Trigger·Transaction
When a check is deposited to Mercury
Pulls from the Mercury transactions API. Tracks check deposits with the payer, amount, and clearing date. Forwarded to Pennylane's email-in with amount, VAT, and date pre-filled by Pennylane's OCR.
Trigger·Transaction
When a wire transfer arrives in Mercury
Pulls from the Mercury transactions API. Captures incoming wires with originator, reference, and value date. Forwarded to Pennylane's email-in with amount, VAT, and date pre-filled by Pennylane's OCR.
Trigger·Transaction
When a new transaction posts on your Mercury account
Pulls from the Mercury transactions API. Triggers on every debit or credit posting in a Mercury account. Forwarded to Pennylane's email-in with amount, VAT, and date pre-filled by Pennylane's OCR.
Trigger·Transaction
When a Mercury account's payment details are read
Pulls from the Mercury transactions API. Resolves the account and routing numbers from the Mercury account so a payment instrument can be matched. Forwarded to Pennylane's email-in with amount, VAT, and date pre-filled by Pennylane's OCR.
Trigger·Payment method
Create a supplier invoice in Pennylane
Driven by Mercury transaction events. Well forwards the extracted PDF to Pennylane's supplier inbox; Pennylane creates the supplier invoice with amount, VAT, and date pre-filled.
Action·Invoice

Reference

Field mapping for Mercury → Pennylane

5 fields across 1 record type, open to see the full table.

Transaction fields

5 fields flow from Mercury into Pennylane.

Mercury field	Label		Pennylane field	Label
transaction.amount	Amount	→	amount	Amount
transaction.currency	Currency	→	currency	Currency
transaction.posted_at	Posted date	→	date	Execution date
transaction.bank_description	Description	→	label	Label
transaction.id	Transaction id	→	external_reference	Source id

Connect Mercury and Pennylane in three steps.

1
Connect Mercury
Click Connect with Mercury; Mercury's MCP server handles authorisation through Dynamic Client Registration. Mercury's MCP server registers a read-scoped Well client through DCR; no credential paste, no shared secret.
- AuthConnect
2
Map your accounts
Well discovers Mercury's transactions, wires, ACH transfers, card payments, and counterparty records and the the Pennylane Purchases tab and the customer-invoice collections list. Counterparty proximity, amount, date, and reference drive the match score; lines above 85% post automatically and the rest queue for a one-click sign-off.
- Auto-post above85% confidence
- Overridemanual anytime
3
Connect Pennylane
Click Connect with Pennylane; Well's OAuth proxy handles Pennylane authorisation through Dynamic Client Registration. Pennylane's MCP server registers a write-scoped Well client through DCR; no credential paste, no shared secret.
- AuthOAuth 2.0
- First syncup to an hour

How Mercury and Pennylane stay secure with Well

Well connects to Mercury through its MCP server, which issues short-lived access tokens via Dynamic Client Registration. Well never holds a long-lived Mercury secret; the server refreshes its own tokens on each session. Well processes records per the storage region configured for your workspace; only fields strictly required by the write surface are ferried across regions.

MCP server authEU residency optionGDPR-aligned

Scopes Well requestsmcp.mercury.com/mcp

Read Mercury records
Scoped to transactions, wires, ACH transfers, card payments, and related records. No access to anything else in your Mercury account.
granted
Deliver documents to your Pennylane inbox
Well forwards the extracted document to your Pennylane email-in address; Pennylane reads supplier and customer invoices via email-in, with amount, VAT, and date pre-filled by Pennylane's OCR from it and you review and post. No write credential to Pennylane is requested.
granted
Modify or delete Mercury records
Not granted. Mercury is read-only on Well's side; the source of truth never moves.
refused
Read other workspaces' data
Encryption keys are per-workspace; another tenant's records are inaccessible by design.
refused

Disconnect any time from Well settings or Mercury’s admin panel.

Frequently asked questions about Mercury and Pennylane on Well

01What Mercury data does Well pull into Pennylane?: Mercury streams transactions, wires, ACH transfers, card payments, and counterparty records to Well over its MCP server. After Well resolves the counterparty and assigns a confidence score, the matched record posts to Pennylane as supplier and customer invoices via email-in, with amount, VAT, and date pre-filled by Pennylane's OCR, with the Mercury event ID preserved on the entry for audit.
02What happens to historical Mercury data when I first connect to Pennylane?: Mercury exposes the last three years through its API on a connected account. The window Well actually pulls is configurable from the integration settings page; each record is matched against your existing Pennylane ledger, and re-running the backfill is safe because Well tracks the Mercury record IDs and updates existing Pennylane entries instead of duplicating them.
03Does Well handle multi-currency records between Mercury and Pennylane?: Mercury reports a single base currency; Well stores the value verbatim and tags the record so your Pennylane ledger can apply its own conversion rule at posting time. Exchange-rate fields are not synthesised, so the Pennylane entry carries the unchanged Mercury amount and the conversion is owned by the Pennylane accounting policy.
04How does Well prevent duplicates when posting Mercury records to Pennylane?: Mercury sends each event with a stable resource ID that Well tracks against the Pennylane ledger. Webhook replays (which Mercury can issue for delivery retries) are recognised by ID and either skipped or used to update the existing Pennylane entry. Distinct records that look similar are caught by Well before posting, with the candidates surfaced in the review queue when confidence is ambiguous.
05What happens if a Mercury record fails to post to Pennylane?: When a record fails to post to Pennylane (validation rule, missing field, transient 5xx), Well retries automatically with backoff. Auth failures short-circuit the retry loop and notify the workspace owner; schema rejections are kept on the integration status page with a one-click retry-after-fix action pointing back at the original Mercury record. Nothing silently drops.
06How does Well authenticate with Mercury and Pennylane?: Mercury's MCP server handles authorisation directly; Well receives an access token through Dynamic Client Registration and never sees raw user credentials. For the delivery side, Well forwards the reconciled document to your Pennylane email-in address once it clears the matching threshold; Pennylane creates the draft record from it and you confirm and post it. Well holds no write credential to Pennylane. Tokens are encrypted at rest and in transit under TLS 1.3. Pennylane hosts in the EU and Mercury hosts outside the EU; Well processes records per the storage region configured for your workspace.