Teller review

Teller is a hosted financial data API that sits between a fintech app and a user’s bank. The app uses Teller to connect an account and retrieve account details, balances and transactions, or to verify ACH details and account-owner identity. Teller also offers APIs for instant payments using Zelle. It is an API service, not a bank account app, local library or self-hosted server.

The homepage shows an HTTP request to an account resource and a JSON response containing account identifiers, institution, status and links to balances, details and transactions. Teller says it connects to more than 7,000 financial institutions; for others, it offers same-day ACH microdeposit verification as a fallback. That puts Teller in the data and payments layer of an application stack. Your app still owns its user experience and business logic, while Teller handles the bank connection and exposes financial data through its API.

The homepage shows a token-authenticated HTTP API with resource-style URLs and JSON responses. Its example retrieves an account at api.teller.io/accounts/{id} and includes links to related balances, details and transactions. The vendor describes the API documentation and guides as comprehensive, and says integration can be completed in an afternoon; treat that as the vendor’s estimate, not a delivery guarantee.

Teller says language bindings are available in a variety of programming languages and offers iOS and Android SDKs for Teller Connect. It does not name the languages on the homepage, so confirm SDK support and current versions in Teller’s docs before choosing a stack. The homepage’s curl example is a command-line way to call the HTTP API; confirm whether Teller provides a dedicated CLI if your workflow depends on one. Teller also advertises Sidecar as a one-line-config-change migration path from Plaid, with no other application updates required. Check that claim against your specific integration and features.

The Developer plan costs $0 and includes 100 live connections for independent developers and teams prototyping ideas. The pricing page says there is no charge within that limit. Production is usage-based: Verify costs $1.50 per account, Balance costs $0.10 per API call, Transactions costs $0.30 per enrollment per month, and Identity costs $1.75 per API call.

Those units make the bill depend on which products an app uses and how often it calls them. For example, balance checks and identity checks are metered per API call, while transaction access is priced per enrollment each month. The pricing page does not list annual billing prices or a single Production starting price. Enterprise uses custom and volume-based pricing and adds options such as a bring-your-own account picker, co-branded consent screens and premium Slack support. Before launch, estimate usage by feature and ask Teller how charges work when a project moves beyond the Developer tier’s 100 live connections.

Teller is presented as a hosted API. Its homepage does not publish an open-source license or a self-hosting option, so teams should not plan to run the service inside their own infrastructure without confirming that directly with Teller. The vendor also does not publish data-export details on the homepage; ask what account, transaction and identity data can be exported, in what format, and for how long it remains available after disconnection.

An integration built around Teller’s account, balance and transaction endpoints will depend on Teller’s API and its institution connections. Teller advertises Sidecar as a one-line configuration change for switching from Plaid, but that is a specific migration claim, not a general portability guarantee. Confirm which data models, consent flows and payment features transfer, and whether your app needs changes if you later replace Teller.

Teller says its connections are stable and keep users connected longer, but the homepage does not publish uptime figures or a service-level agreement. It also does not publish API rate limits, so ask about per-endpoint limits, retry guidance and behavior during institution outages before setting production traffic expectations. Coverage above 7,000 institutions is broad, but an app still needs a fallback for users whose institution is not supported; Teller cites same-day ACH microdeposit verification for those cases.

Usage-based charges can scale with API calls and enrollments, so monitor metered features against your budget. Enterprise customers can request customizable account refresh schedules. The homepage lists SOC 2 Type 2 certification under Enterprise; confirm the scope and available security documentation during procurement. Ask about incident response, data retention, encryption and service availability as part of the same review rather than treating coverage claims as a reliability commitment.