What Mercury data does Well pull into Melio?

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 Melio as bills via email-in at @invoicesmelio.com, with vendor, amount, and due date populated by Smart Bill Capture, with the Mercury event ID preserved on the entry for audit.

How often does Mercury data sync to Melio?

Mercury pushes events to Well over its MCP server, so most records land within seconds of the underlying action. Each event is matched immediately and reaches Melio within a confidence window: above 85% it posts, 55-85% queues for review, below 55% is refused.

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

Mercury reports a single base currency and Melio ledgers in a single base currency, so Well stores the value verbatim and posts the record without any conversion step. If you start trading in another currency, switch the connector behaviour in settings and Well begins tagging records with the source currency for conversion at posting time.

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

Mercury sends each event with a stable resource ID that Well tracks against the Melio ledger. Webhook replays (which Mercury can issue for delivery retries) are recognised by ID and either skipped or used to update the existing Melio 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 I disconnect Mercury or Melio?

Disconnecting Mercury stops the flow at the source. Well asks the Mercury MCP server to revoke the access token; Mercury returns confirmation and stops streaming events the moment it is acknowledged. Anything you already reviewed and posted in Melio is Melio's own record and is untouched; Well never held a write credential to it. Records held for review in Well remain in the queue so you can finish them by hand. Reconnecting later resumes from the last successful sync, not from scratch.

How does Well authenticate with Mercury and Melio?

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 Melio email-in address once it clears the matching threshold; Melio creates the draft record from it and you confirm and post it. Well holds no write credential to Melio. Tokens are encrypted at rest and in transit under TLS 1.3. Mercury and Melio together cover multiple regions; Well's storage region is configured per workspace.

Mercury to Melio

AvailableNative · MercuryNative · Melio

Connect Mercury to Melio with Well

Pair Mercury statement activity with Melio bills inside Well so duplicate-debit signals fire before a second hit reaches the bank.

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.

Melio

Target

The Melio connection delivers extracted bills into Melio through its Pay Bills email address.

Why this pair

Connect Mercury to Melio through Well so records flow without manual rework.

What Well does between Mercury and Melio

One-way: Mercury into Well into Melio
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

Anthropic UK

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

CounterpartyAnthropic UK
Booking date22 Apr 2026
Amount$1,284.00
CurrencyUSD
ReferenceINV-1024

Enrich

against your historical record graph

4 fields added

CounterpartyAnthropic UK
Tax idGB413028562
Ledger account6156 · AI services
Match1 candidate invoice

Confidence97%

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

Post

schedule as bills

Create a bill in your Melio inbox

auto-posted

posted

TypeBill
VendorAnthropic UK
Amount$1,284.00
Ledger6156 · AI services
Source docattached
Confidence97%

audit linkto Melio

Action in Melio

1 compatible with this trigger

Create a bill in your Melio inbox

Match Mercury debits to Melio scheduled payments.

01Featured

Match debits to bills you have in flight

Each Mercury debit is checked against your bill records inside Well on payee, amount, scheduled date, and currency. Above the auto-link threshold the bank line is linked inside Well; AP sees the link in the document Well forwards to Melio, with the receipt attached for the next vendor audit.

Flag unauthorised vendor payments

If a Mercury debit appears for a vendor not on your approved list inside Well, the match is stopped and the workspace owner is paged. The debit sits on a review queue with the proposed new vendor alongside; once confirmed, Well treats the next debit from the same counterparty consistently before forwarding to Melio.

Confirm bills paid outside of Melio

Vendors sometimes get paid directly from Mercury without going through Melio (manual transfers, wire requests). Well detects these by counterparty plus amount and surfaces them in its own queue so AP can close the loop in Melio without recreating the payment.

Surface duplicate payments before the second debit

If a bill flips to scheduled twice in error, Well watches the next Mercury debit window for a second payment to the same vendor with the same amount and surfaces the conflict before AP confirms the second action in Melio.

12 signals and actions across Mercury and Melio

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.
Trigger·Account
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.
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.
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.
Trigger·Payment method
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.
Trigger·Transaction
When a Mercury card charge posts
Pulls from the Mercury transactions API. Captures debit card transactions with merchant and MCC code.
Trigger·Transaction
When a wire transfer arrives in Mercury
Pulls from the Mercury transactions API. Captures incoming wires with originator, reference, and value date.
Trigger·Transaction
When a wire transfer is sent from Mercury
Pulls from the Mercury transactions API. Tracks outbound wires with beneficiary detail and instruction.
Trigger·Transaction
Attach the bill PDF to the Melio record
Driven by Mercury transaction events. The forwarded PDF is stored on the bill in your Melio inbox.
Action·Document

Reference

Field mapping for Mercury → Melio

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

Transaction fields

5 fields flow from Mercury into Melio.

Mercury field	Label		Melio field	Label
transaction.amount	Amount	→	amount	Amount
transaction.currency	Currency	→	currency	Currency
transaction.posted_at	Posted date	→	scheduled_for	Payment date
transaction.bank_description	Description	→	reference	Reference
transaction.id	Transaction id	→	payment_id	Payment id

Connect Mercury and Melio 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 Melio Bills Inbox awaiting payment scheduling. The first batch of bank lines flows into the review queue alongside candidate scheduled payments; once you confirm the rule, Mercury debits auto-link above 85% confidence.
- Auto-post above85% confidence
- Overridemanual anytime
3
Connect Melio
In Melio, open Settings > Integrations and generate an API token with payment-write scope. Paste the key into Well; Melio's discovery endpoints are reached over TLS 1.3 and the secret is never echoed in the UI.
- AuthConnect
- First sync~10 min

How Mercury and Melio 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's storage region is configured per workspace regardless of where Mercury and Melio host theirs.

MCP server authStorage region per workspaceGDPR-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 Melio inbox
Well forwards the extracted document to your Melio email-in address; Melio reads bills via email-in at @invoicesmelio.com, with vendor, amount, and due date populated by Smart Bill Capture from it and you review and post. No write credential to Melio 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 Melio on Well

01What Mercury data does Well pull into Melio?: 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 Melio as bills via email-in at @invoicesmelio.com, with vendor, amount, and due date populated by Smart Bill Capture, with the Mercury event ID preserved on the entry for audit.
02How often does Mercury data sync to Melio?: Mercury pushes events to Well over its MCP server, so most records land within seconds of the underlying action. Each event is matched immediately and reaches Melio within a confidence window: above 85% it posts, 55-85% queues for review, below 55% is refused.
03Does Well handle multi-currency records between Mercury and Melio?: Mercury reports a single base currency and Melio ledgers in a single base currency, so Well stores the value verbatim and posts the record without any conversion step. If you start trading in another currency, switch the connector behaviour in settings and Well begins tagging records with the source currency for conversion at posting time.
04How does Well prevent duplicates when posting Mercury records to Melio?: Mercury sends each event with a stable resource ID that Well tracks against the Melio ledger. Webhook replays (which Mercury can issue for delivery retries) are recognised by ID and either skipped or used to update the existing Melio 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 I disconnect Mercury or Melio?: Disconnecting Mercury stops the flow at the source. Well asks the Mercury MCP server to revoke the access token; Mercury returns confirmation and stops streaming events the moment it is acknowledged. Anything you already reviewed and posted in Melio is Melio's own record and is untouched; Well never held a write credential to it. Records held for review in Well remain in the queue so you can finish them by hand. Reconnecting later resumes from the last successful sync, not from scratch.
06How does Well authenticate with Mercury and Melio?: 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 Melio email-in address once it clears the matching threshold; Melio creates the draft record from it and you confirm and post it. Well holds no write credential to Melio. Tokens are encrypted at rest and in transit under TLS 1.3. Mercury and Melio together cover multiple regions; Well's storage region is configured per workspace.