--- url: https://marimo-team.github.io/marimo-studio/reference/limits.md description: >- File, source, provider, projection, payload, output, and timeout limits enforced by Studio. --- # Limits Studio bounds source inspection, provider processes, build snapshots, browser artifacts, projection requests, and validation waits. Limits apply before publication or mutation commit unless the table names a browser boundary. ## Names and Source documents | Boundary | Limit | Failure or diagnostic | | ----------------------------------------------------- | --------------: | ------------------------------------------------- | | View name | 238 UTF-8 bytes | `configuration-error` or an inline creation error | | Source document | 64 MiB | `source-too-large` | | Source encoding | UTF-8 | `invalid-source-encoding` | | Source documents returned by one provider inspection | 256 | Provider conformance error | | Provider path, title, summary, message, or hint field | 64 KiB UTF-8 | Provider conformance error | View names also follow the syntax and reserved-name rules in [View projects](configuration.md#view-projects). Source paths follow [Source documents and build inputs](configuration.md#source-documents-and-build-inputs). ## Build inputs and artifacts | Boundary | Files | Per file | Total | | ----------------------------- | ----: | -------: | ------: | | Declared project build inputs | 4,096 | 64 MiB | 512 MiB | | Published artifact | 4,096 | 128 MiB | 1 GiB | Studio rejects symlinks and path collisions that violate the contained project or artifact contract. Artifact validation also rejects reserved routes, a missing entry document, and a document without one `head`, one `body`, and one `#app-shell`. Static export combines the artifact with Studio runtime assets and notebook public files. Prepared export adds verified output assets within marimo-export's 64 MiB asset and 512 MiB export limits. Browser export adds notebook source. Studio checks each copied tree against the artifact file budget before the staged directory replaces the destination. ## Projection declarations | Boundary | Limit | | ------------------------------------------------ | ----------------: | | Projection sites returned by provider inspection | 512 | | Encoded projection sites | 1 MiB | | Finite cell targets on one site | 256 | | Finite output targets on one site | 100 | | Finite value targets on one site | 100 | | Projection target | 4,096 UTF-8 bytes | | Value selector path | 64 steps | | Media types in one output accept list | 32 | Value selectors and accept lists follow marimo-export's [`values`](https://marimo-team.github.io/marimo-export/reference/python/values) module, which a Prepared export also uses. A `"*"` target marks a dynamic site, so inspection skips enumerating its targets. Runtime policy still applies to active instances and unique targets. Prepared export requires finite targets on every site. ## Renders | Boundary | Limit | Failure | | ----------------------------------------- | ------: | -------------------------------- | | Renders declared by one view | 32 | Provider conformance error | | Encoded render values for one render | 8 MiB | `render-values-too-large` | | Outputs and cells read by one render | 16 MiB | `render-outputs-too-large` | | Files returned by one render | 1,024 | Provider conformance error | | One rendered file | 512 MiB | `render-too-large` | | All files returned by one render | 1 GiB | `render-too-large` | | Provider commands during one render | 300 s | `render-failed` | | Renders across one static export's states | 256 | `render-states-exceeded` | | Regions kept from one render | 4,096 | `render-regions-limited` warning | | Reads kept by one region | 64 | Later reads left out | | UTF-16 code units in one region label | 256 | Label shortened | ## Active presentation projections | Boundary | Limit | Browser diagnostic | | --------------------------- | ----------------: | -------------------------------- | | Active projection instances | 512 | `projection-instance-limit` | | Unique cell targets | 256 | `projection-cell-target-limit` | | Unique output targets | 100 | `projection-output-target-limit` | | Unique value targets | 100 | `projection-value-target-limit` | | Projection instance ID | 256 UTF-8 bytes | Projection resolution error | | Projection target | 4,096 UTF-8 bytes | Projection resolution error | | Value selector path | 64 steps | Projection resolution error | A complete cell or rendered output target accepts one host, and duplicate hosts enter an error state. Several `mo-value` hosts may share one value target. ## Runtime payloads | Boundary | Limit | Failure | | ------------------------------------------------- | --------------: | ------------------------------------------ | | Encoded browser runtime configuration | 16 MiB | `runtime-config-too-large` | | One projected JSON value | 1,000,000 bytes | `value-too-large` | | Values and keys in one projected JSON value | 100,000 values | `value-too-large` | | JSON values in one value read | 1,000,000 bytes | `response-too-large` | | One projected Arrow value | 64 MiB | `value-too-large` | | Arrow values in one value read | 128 MiB | `response-too-large` | | Arrow values in one Browser runtime value read | 64 MiB | `response-too-large` | | One rendered output, and the outputs of a request | 5,000,000 bytes | `output-too-large` or `response-too-large` | | One rendered output request set | 100 selectors | Capability or protocol error | | Browser client response | 5,000,000 bytes | Live request failure | The Python and Browser runtimes enforce the value limits. A value read carries the values that a view projects from one producer cell, and `marimo-studio validate --level runtime` reads them the same way. Eager pandas, Polars, and PyArrow tables travel as [Arrow IPC](https://arrow.apache.org/docs/format/Columnar.html#serialization-and-interprocess-communication-ipc), a columnar binary format. Collect lazy dataframes in the notebook before projecting them. Other values travel as JSON, so return a table to project more than 1,000,000 bytes. The Python runtime publishes Arrow values through marimo's shared memory. A container's default 64 MiB `/dev/shm` holds about one large value, so start containers with a larger `--shm-size`. A value that does not fit travels inline and takes longer to load. The Browser runtime passes Arrow values from its worker as base64 text, which caps a value read there at 64 MiB of Arrow. `marimo-studio validate --level runtime` applies the Python runtime budgets. The Prepared runtime stores each value as a [marimo-export](https://github.com/marimo-team/marimo-export) asset. One asset holds at most 64 MiB, and one export holds at most 512 MiB of unique assets across its prepared states. Browser runtime configuration contains saved notebook source, projection declarations, runtime bindings, and presentation settings. Prepared runtime configuration contains the publication identity and manifest URL. When a Browser record reaches 16 MiB, use finite projection targets and reduce notebook source. ## Provider records | Boundary | Limit | | ----------------------------------------- | ----------------------------: | | Starters per provider | 256 | | Source documents per starter | 256 | | Options in one view project | 256 | | Cell targets consumed by one starter plan | 256 | | Provider inspection diagnostics | 512 records and 1 MiB encoded | | Provider build diagnostics | 512 records and 1 MiB encoded | | Encoded third-party operation request | 128 MiB | | Encoded third-party operation result | 16 MiB | Provider titles, summaries, option values, paths, diagnostics, starter files, and notebook context also pass structural and byte validation. The [View provider API](provider-api.md) defines the record responsibilities. ## Timeouts | Operation | Default | Accepted range or budget | | ------------------------------------------------------------------ | ----------: | -----------------------------------------------------------------------------: | | Runtime inspection and validation | 60 seconds | Greater than 0, up to 300 seconds | | Prepared export | 30 seconds | Positive duration | | Provider runner command | 120 seconds | Finite positive duration within the request's shared 120-second command budget | | Third-party provider metadata, availability, and starter discovery | 10 seconds | Fixed extension-operation deadline | Runtime workers get an additional 10-second shutdown allowance after the requested runtime timeout. A timeout bounds waiting and cleanup ownership. It does not restrict the operating-system authority of notebook or provider code. ## Browser message bounds Navigation and public query synchronization accept at most 16 KiB of query text and 8 KiB of URL fragment text. Studio validates messages between the trusted presentation shell and the opaque-origin authored frame before changing history or runtime state.