As part of the OpenFEMA initiative, FEMA is providing read-only API based access to datasets (Entities). The data is exposed using a RESTful interface that uses query string parameters to manage the query. Use of the service is free and does not require a subscription or API key.
This document provides information on how to use the API including command examples. The examples shown are HTTP requests. Other methods such as CURL or accessing with a programming language can also be used. See the Developer Resources page for additional information.
A full list of Entities/endpoints supported by the API can be found at Data Sets.
Major and minor version features (including the addition or deprecation of datasets) can be found on the Changelog page.
Basics
The base path for the API endpoints is https://www.fema.gov/api/open.
To use the API, you will need to build a query string path in the following format:
[base path]/[version]/[entity]
- version: To support future enhancements we are using a versioning system for the APIs. To use the APIs you must indicate which version you need. The API version format is v1, v2, v3, etc.
- entity: This corresponds to the name of the entity set you are requesting. The entity names can be found in the list of released datasets.
Example: https://www.fema.gov/api/open/v2/DisasterDeclarationsSummaries
Query strings including the data set/endpoint name are case sensitive.
Query strings including the data set/endpoint name are case sensitive.
A successful response will include a both a metadata object (described below) and an array of entity objects (records). By default, only 1,000 records are returned. See the URI commands below for information on how to page through all found records. Working examples can be found on the Developer Resources page.
URI Quick Reference
| Command | Description | Default |
| $allrecords | BETA. To specify that all records are to be returned when downloading data. | false (only records up to $top returned) |
| $count | To specify if a total entity count should be returned with the query. | false (the count is not returned) |
| $filename | To specify the download filename. | |
| $filter | To filter or limit the results returned. | All records up to $top returned |
| $format | To specify the format of the returned data. | JSON |
| $inlinecount | DEPRECATED. See the $count parameter. To specify if a total entity count should be returned with the query. | none (the count is not returned) |
| $metadata | Controls the presence of the metadata object in data set returns. | on (metadata is returned) |
| $orderby | Sort the returned data. | |
| $select | To specify the fields to return. | All fields returned |
| $skip | Number of records to skip from the dataset. | 0 |
| $top | Limit the number of records returned. | 1,000 (maximum is 10,000) |
URI Commands Reference
A Uniform Resource Identifier (URI) is a string of characters identifying an abstract or physical resource on the web. This can be a URL to a website; it can also be identify a specific resource as well as a location. The following URI commands can be used to alter your request of OpenFEMA endpoint data – filtering the result, specifying a return type, or including additional metadata.
A full download link selected from the dataset page or a file type appended to an endpoint will perform a full download. Adding parameters after the file extension will have no effect. If you want to specify a parameter, even for a full download, do not use the file extension shortcut.
Do not do this:
v1/DeclarationDenials.csv?$orderby=state
Do this instead:
v1/DeclarationDenials?$format=csv&$orderby=state
Search
Performs a search of the entity using specified query string parameters.
Query String Parameters
$allrecords
BETA. This query argument forces all records to be returned as part of a download rather than adhering to the maximum return limit. It is an attempt to reduce the difficulty in downloading large sets of data. Currently, any query resulting in more records than specified by $top will require a "paging" technique to iterate through results to capture all of the data. The $allrecords=true query string overrides this behavior.
Note, this will not have the effect of retrieving and displaying all records within a browser window. It must be used in conjunction with a file download as shown in the following example.
This is being released as a BETA feature. If we find it negatively impacts OpenFEMA system performance, it may be removed.
Valid values are:
- true - Returns all records matching criteria as part of a download
- false - Returns only the number of records matching $top (default)
Example
- /api/open/v2/DisasterDeclarationsSummaries?$format=csv&$filename=DDSV2_all.csv&$allrecords=true - Saves all 65K+ records to the designated file.
Query option that controls if a total count of all entities matching the request MUST be returned as part of the result. If the $count parameter is not supplied, no count will be returned; it will appear as “0”. Note, this parameter is a replacement for the $inlinecount parameter.
If retrieving large amounts of data or using complex $filter criteria through a "paging" technique, avoid specifying "$count=true" in each call. This will result in faster queries.
Valid values are:
- true - Returns the count
- false - Does not return the count (default)
Example
- /api/open/v2/DisasterDeclarationsSummaries?$count=true - Returns the record count
- /api/open/v2/DisasterDeclarationsSummaries?$count=false - Returns without the record count (i.e., a record count of 0)
- /api/open/v2/DisasterDeclarationsSummaries - (Default) Returns without the record count (i.e., a record count of 0)
Allows for the specification of a download filename. The data downloaded will be limited to fields specified using $select (all fields if none specified), will contain records limited by $filter, and will be sorted according to the $orderby parameter. Note, all of the $filter, $orderby, and $select parameters will work with $filename. The filename should not be surrounded by quotation marks even if the filename contains spaces. If no $format parameter is specified, JSON will be the result.
Example
- /api/open/v1/DataSets?$filename=OpenFEMADatasets.txt - Returns data set metadata and initiates a download to a filename called “OpenFEMADatasets.txt”. Even though a “txt” extension has been provided, data will default to a JSON format as no $format parameter was specified.
- /api/open/v1/DataSets?$select=identifier,name&$filter=lastRefresh gt '2020-05-01'&$orderby=name&$filename=DataSetList.json - Returns data set metadata and initiates a download to a filename called “DataSetList.json”. Only dataset identifiers and names will be returned for those that were last refreshed after 05-01-2020 and sorted by name.
Used to "filter" the results returned. The API provides a number of operations that can be used to build your request. The API provides as subset of the available options in the OData specification. Please note that dates should be represented in an ISO-8601 format.
The query parser is very strict. Ensure your spacing, quoting, and capitalization are correct.
Spaces are required between logical operators.
Strings must be single quoted.
URL encoding (e.g., %20, %24, %27, etc.) may be used.
Any string containing a quote (e.g., bob's burgers) must have the quote doubled to have an effect (e.g., bob''s burgers).
Logical Operators:
Grouping Operators:
This represents logical operator grouping, not data aggregation.
| Operator | Description | Example |
| ( ) | Precedence grouping | /DisasterDeclarationsSummaries?$filter=(state eq 'VA' and designatedArea eq 'Alleghany (County)') or disasterNumber eq 1570 |
String Functions:
To enable filtering on partial strings.
| Function | Example |
| bool substringof(string searchString, string searchInString) | /DisasterDeclarationsSummaries?$filter=substringof('OO',declarationTitle) |
| bool endswith(string string, string suffixString) | /DisasterDeclarationsSummaries?$filter=endswith(declarationTitle,'ING') |
| bool startswith(string string, string prefixString) | /DisasterDeclarationsSummaries?$filter=startswith(declarationTitle,'FLO') |
Special Functions:
To permit searching within objects, including geospatial operations.
Controls the format of the returned data.
Supported values include:
- json - Returns data in the JavaScript Object Notation format (default)
- jsona - Returns data as a JavaScript Object Notation array format (no top-level object)
- geojson - Returns data as a JavaScript Object Notation format encoded with geographic data structures. NOTE: This format will only work if the dataset supports geospatial data
- csv - Returns data in a Comma-Separated Value format. Metadata is not returned when using CSV format.
- parquet – Returns data as a column-oriented data file. This format is designed for efficient data storage and retrieval and works well with programming constructs in languages like R or Python. Currently, no encoding is applied, and data is compressed with the Snappy format.
Example
- /api/open/v2/DisasterDeclarationsSummaries?$format=json - Data is returned in JSON format
- /api/open/v2/DisasterDeclarationsSummaries?$format=jsona - Data is returned in JSONA format
- /api/open/v2/DisasterDeclarationsSummaries?$format=csv - Data is returned in JSON format
- /api/open/v2/FemaRegions?$format=geojson - Data is returned in a geospatial encoded GEOJSON format
- /api/open/v1/FemaWebDisasterDeclarations?$format=parquet - Data is returned in a column-oriented parquet format
DEPRECATED. This parameter will remain for several months but is being replaced by $count. This will add clarity to the returned metadata object and is more in-line with OData standards.
Query options that controls if a total count of all entities matching the request MUST be returned as part of the result. Note, if the $inlinecount parameter is not supplied, no count will be returned; it will appear as “0”.
If retrieving large amounts of data or using complex $filter criteria through a "paging" technique, avoid specifying "allpages" in each call. This will result in faster queries.
Valid values are:
- allpages - Returns the count
- none - Does not return the count (default)
Example
- /api/open/v2/DisasterDeclarationsSummaries?$inlinecount=allpages - Returns the record count
- /api/open/v2/DisasterDeclarationsSummaries?$inlinecount=none - Returns without the record count (i.e., a record count of 0)
- /api/open/v2/DisasterDeclarationsSummaries - (Default) Returns without the record count (i.e., a record count of 0)
Controls the presence of the data set metadata object with a returned data set. Note, only applies if the format is JSON. If the format is CSV, no metadata is returned.
Supported values include:
- on or true– Returns the metadata object for data returned in a JSON format (default)
- off or false – Suppresses the metadata object for data returned in a JSON format
Example
- /api/open/v2/DisasterDeclarationsSummaries?$metadata=off - This will cause the metadata object to be suppressed.
Allows for the sorting of data on the server. By providing a comma separated list of fields and a sort direction you can control the order that data is returned. Available sort directions are “asc” and “desc” for ascending or descending respectively. If no direction is provided, ascending is the default.
Example
- /api/open/v2/DisasterDeclarationsSummaries?$orderby=state - Sorts data by state in ascending order.
- /api/open/v2/DisasterDeclarationsSummaries?$orderby=state desc, designatedArea - Sorts data by the state field in descending order and by county in ascending order
Used to specify which fields you would like returned in your dataset. Providing a comma separated list of case sensitive field names will return just those fields. If no value is specified, all of the fields are returned.
Example
- /api/open/v2/DisasterDeclarationsSummaries?$select=disasterNumber,state,declarationType - returns only the disasterNumber, state, and declarationType fields.
- /api/open/v2/DisasterDeclarationsSummaries?$select=disasterNumber,state,incidentBeginDate,incidentEndDate - returns only the disasterNumber, state, incidentBeginDate, and incidentEndDate fields.
Number of records to skip from the dataset. Used in conjunction with $top to allow you to page through the dataset. See the Developer Resources page for working examples of iterating through a result set to capture all the data matching the specified criteria. If no value is specified, $skip defaults to 0 and starts at the beginning of the results set.
Example
- /api/open/v2/DisasterDeclarationsSummaries?$skip=500 - This will return the first 500 records from the query and begin returning results starting with the 501st record
- /api/open/v2/DisasterDeclarationsSummaries?$skip=100 - This will return the first 100 records from the query and begin returning results starting with the 101st record
Limits the number of records returned. Currently the default value is 1,000 records. The maximum value is 10,000 records. See the Developer Resources page for working examples of iterating through a result set to capture all the data matching the specified criteria.
Example
- /api/open/v2/DisasterDeclarationsSummaries?$top=50 - This will return the first 50 records from the query
- /api/open/v2/DisasterDeclarationsSummaries?$top=10 - This will return the first 10 records from the query
Get By ID
Retrieves a specific record identified by its ID field (id).
Query string format is:
/api/open/[version]/[entity]/[_id]
- version: To support future enhancements we are using a versioning system for the APIs. To use the APIs you must indicate which version you need. The API version format is v1, v2, v3, etc.
- entity: This corresponds to the name of the entity set you are requesting. The entity names can be found in the list of released datasets.
- _id - This is a _id value of a previously identified record in an entity.
Example:
Query String Parameters
$format
Controls the format of the returned data.
Supported values include
- json - Returns data in the JavaScript Object Notation format (default)
- csv - Returns data in a Comma-Separated Value format
- jsona - Returns data as a JavaScript Object Notation array format
- geojson - Returns data as a JavaScript Object Notation format encoded with geographic data structures. NOTE: This format will only work if the dataset supports geospatial data
- parquet – Returns data as a column-oriented data file
Example
- https://www.fema.gov/api/open/v2/FemaRegions/8a8064df-f1f7-4f0c-a3ae-b31fce82778b?$format=json - Data is returned in JSON format
- https://www.fema.gov/api/open/v2/FemaRegions/8a8064df-f1f7-4f0c-a3ae-b31fce82778b?$format=jsona - Data is returned in JSONA format
- https://www.fema.gov/api/open/v2/FemaRegions/8a8064df-f1f7-4f0c-a3ae-b31fce82778b?$format=csv - Data is returned in CSV format
Metadata
A successful response will include a metadata object along with the array of entity objects. Most of the metadata corresponds to the URI commands and parameters specified above. The metadata object can be suppressed by using the $metadata parameter.
| Metadata | Description |
|---|---|
| skip | Number of records skipped as specified by the $skip parameter. If the $skip parameter was not used, this value will be 0. |
| top | Max number of records returned as specified by the $top parameter. If the $top parameter was not used, this value will be 1,000. The maximum that can be specified is 10,000. |
| count | Count of all possible records found matching any provided criteria. If the $count parameter was not used, or “none” was specified, this value will be 0. If the count returned is greater than the maximum value specified by $top, you will need to implement a paging strategy to return all the records that match the criteria specified. |
| filter | Filter values applied as specified by the $filter parameter. |
| format | Format of the data as specified by the $format parameter. If none specified, the format will default to JSON. |
| metadata | Indicates if the metadata object suppression parameter has been specified. |
| orderby | Sort order for the data as specified by the $orderby parameter. |
| select | Fields specified for return as specified by the $select parameter. |
| entityname | Name of the entity or endpoint for which data was queried. |
| version | The API endpoint version used to return the data. |
| url | The fully composed URL used to return the data. |
| rundate | The date and time when the API call was executed. |
| DeprecationInformation | (optional) An object containing the following 4 metadata items. Only appears when the dataset has been deprecated. |
| depDate | (optional) Only appears when the data set has been deprecated. Indicates that the data set has been deprecated and will be removed by this date. |
| depApiMessage | (optional) Only appears when the data set has been deprecated. Provides additional information about the deprecation of the data set. |
| depNewURL | (optional) Only appears when the data set has been deprecated. Provides a link to an API endpoint that will supersede this dataset (if one exists). |
| depWebMessage | (optional) Only appears when the data set has been deprecated. Provides additional information about the deprecation of the data set as it appears on the dataset webpage. |
Special Dataset Fields
As a matter of policy, the OpenFEMA API does not enrich data from source systems. However, up to four fields are added by OpenFEMA either for internal purposes or to aid users in refreshing data. While the fields are briefly described in each dataset data dictionary, confusion about these fields has necessitated a more thorough description.
Datasets internally are classified as RELOAD or UPDATE. RELOAD datasets follow a drop and reload process while UPDATE datasets add new records or update existing records that have changes. Existing records without a change are left unmodified in OpenFEMA. Reloads and updates occur according to the dataset refresh frequency/schedule. Those that are fully reloaded will not contain a hash or lastRefresh value.
id
This is not a unique identifier from the source system. It is an OpenFEMA generated unique identifier assigned to the record that does not persist between dataset refreshes. It can be used as a unique id within the immediate set of downloaded records. However, following the next data refresh, there is no guarantee that the id will remain the same for the for the same record.
Why not use source system identifiers? Some datasets are aggregated, thereby negating the use of a source system id. Some combine data from multiple sources and no one identifier can be used. Some datasets have no available unique identifier. Some source systems consider their identifiers as “sensitive” and are not made available to OpenFEMA.
If you require some kind of source system unique identifier, query the OpenFEMA DataSetFields metadata API and review the primaryKey element to identify those fields contributing to a record's uniqueness. All the fields that have this flag set to true must be used to uniquely identify the record. If none of the dataset fields has the primaryKey value set, the record has no source system identifier available within this dataset. For example, the following query against the Disaster Declarations Summaries dataset will indicate that the declarationNumber in combination with the placeCode will uniquely identify a record: https://www.fema.gov/api/open/v1/DataSetFields?$filter=openFemaDataSet%20eq%20%27DisasterDeclarationsSummaries%27%20and%20datasetVersion%20eq%202%20and%20primaryKey%20eq%20true
hash
An SHA1 hash of the field values of the record. If anything in a record changes—even capitalization, spacing, or punctuation—the SHA1 value will change. OpenFEMA uses this internally to identify changes to records to aid in updates. We have exposed this to the users because someone might find it useful. It should not be used as a record identifier.
lastRefresh
The lastRefresh value in any of the datasets indicates the last date/time the record was added or changed in the OpenFEMA data store from the FEMA source system. It is possible to use this information to query recent data rather than performing a full dataset download. Note that this value does not indicate when the source system data was updated, only when the OpenFEMA record was updated. In addition, datasets that do not contain this field are refreshed by performing a full reload on all the data; there is no way to tell when an individual record was added or updated.
For the DataSets dataset, the lastRefresh value indicates the same – the last date/time the record was added or changed. In this dataset, each record contains the metadata attributes for an individual dataset. Therefore, the lastRefresh value reflects the last date/time the record (i.e., an individual dataset’s metadata) was updated or changed.
Whether you are refreshing the entire dataset or just trying to add or update changed records since the last update, your refresh interval should not be more frequent than the dataset refresh interval. Further, it would be prudent to check the dataset update status prior to executing your own refresh. There may be situations when the OpenFEMA data store is unable to refresh from the source data. See OpenFEMA Guide to Working with Large Data Sets | Appendix B - Checking for Data Updates for a more thorough discussion of using this field to perform updates. See API Tutorial Part 5 Getting Dataset Updates (OpenFEMA GitHub | API Tutorials) for working code examples.
Whether you are refreshing the entire dataset or just trying to add/update changed records since the last update, your refresh interval should not be more frequent than the dataset refresh interval. Further, it would be prudent to check the dataset update status prior to executing your own refresh. There may be situations when the OpenFEMA data store is unable to refresh from the source data.
lastDataSetRefresh
The lastDataSetRefresh value is only found in the DataSets dataset and indicates the last date/time the individual dataset that the record represents was refreshed/reloaded in the OpenFEMA data store from the FEMA source system. Note that this value does not indicate if any records within the individual dataset have been added or changed, only that the dataset refresh/reload process completed. It is possible to use this information to query only recently refreshed datasets rather than performing frequent blind downloads.
OpenAPI Specification
An API specification defines how an API functions and the results to expect when using the API. Usually, API specifications are associated with documentation. They do more however, providing an understanding of API behavior especially with regard to links with other API’s. Specifications define machine-readable interface files for describing, producing, consuming, and visualizing RESTful web services. Once defined, tools exist to generate documentation, code stubs, and test cases for a given interface.
The “official” OpenFEMA API documentation is available on fema.gov. Additionally, two special endpoints (DataSets and DataSetFields) also exist to provide metadata in a machine-readable format. To enhance the OpenFEMA metadata capabilities, an endpoint has been created to provide an OpenAPI Specification v3.0 file. This format will allow for the experimentation and testing of the OpenFEMA API endpoints directly from a visual interface.
The base path for the OpenAPI metadata endpoint is: https://www.fema.gov/api/open/metadata/v3.0/OpenApi
A file type suffix must be added to the base path. Supported file types are:
- json – returns data in a JSON format
- yaml – returns data in a YAML format
Example
See Also