# /sra/experiments/search

`POST /api/sra/experiments/search`

Price: 20 credits

Search SRA sequencing experiments by query and library filters

## How to use it

Searches the Sequence Read Archive at experiment level - one row per sequencing library, with its runs nested. The library facets are the useful ones: `strategies` says what the experiment measures (RNA-Seq, WGS, ATAC-seq), `sources` says what material it came from, and the single-cell distinction lives in `sources` rather than in `strategies`. `accession` matches at any level, so a study accession returns every experiment under it. A misspelt bracket tag inside `term` is not rejected - it falls through to a free-text match and quietly widens the result set, so prefer the structured fields. Results come back in the archive's own order; there is no ranking to request.

## Parameters

- `access-token` (string, required)

## Request body

- `timeout` (integer) — Max scrapping execution timeout (in seconds) (default: 300; min: 20; max: 1500)
- `term` (string, nullable) — Free-text query in Entrez syntax. Supports bracketed field tags (human[Organism], RNA-Seq[Strategy]), boolean AND/OR/NOT and year ranges (2018:2022[PDAT]). Combined with AND against every structured filter below (examples: "single cell brain", "tumor AND RNA-Seq")
- `count` (integer, required) — Number of experiments to return (min: 1; max: 5000)
- `offset` (integer) — How many matches to skip before the returned page, for walking past a single call's ceiling (default: 0; min: 0; max: 100000)
- `organism` (string, nullable) — Filter by source organism, scientific or common name (examples: "Homo sapiens", "human")
- `experiment_title` (string, nullable) — Filter by words in the experiment title (examples: "RNA-Seq")
- `author` (string, nullable) — Filter by submitting author (examples: "Smith J")
- `accession` (string, nullable) — Filter by an SRA accession of any level (experiment, study, sample or run) (examples: "SRX1234567", "SRP011949")
- `bioproject` (string, nullable) — Filter by the BioProject the experiments belong to (examples: "PRJNA157243")
- `biosample` (string, nullable) — Filter by the BioSample the library was built from (examples: "SAMN03898702")
- `platforms` (array, nullable) — Filter by sequencing platform (any-of) (one of: "illumina", "oxford_nanopore", "pacbio_smrt", "ion_torrent", "bgiseq", "dnbseq", "capillary", "abi_solid", "ls454", "helicos", "complete_genomics", "element", "ultima", "genapsys", "tapestri", "vela_diagnostics", "singular_genomics")
- `strategies` (array, nullable) — Filter by what the library was built to measure (any-of) (one of: "wgs", "wga", "wxs", "rna_seq", "mirna_seq", "ncrna_seq", "ssrna_seq", "atac_seq", "chip_seq", "bisulfite_seq", "amplicon", "clone", "poolclone", "cloneend", "finishing", "mnase_seq", "dnase_hypersensitivity", "est", "fl_cdna", "cts", "mre_seq", "medip_seq", "mbd_seq", "tn_seq", "validation", "faire_seq", "selex", "rip_seq", "chia_pet", "synthetic_long_read", "targeted_capture", "tethered_chromatin_conformation_capture", "hi_c", "ribo_seq", "other")
- `sources` (array, nullable) — Filter by the kind of material the library came from (any-of) (one of: "genomic", "transcriptomic", "metagenomic", "metatranscriptomic", "synthetic", "viral_rna", "genomic_single_cell", "transcriptomic_single_cell", "other")
- `selections` (array, nullable) — Filter by the method used to select the molecules that were sequenced (any-of) (one of: "random", "pcr", "random_pcr", "rt_pcr", "hmpr", "mf", "mda", "msll", "cdna", "chip", "mnase", "dnase", "hybrid_selection", "reduced_representation", "restriction_digest", "methylcytidine_antibody", "mbd2_protein_methyl_cpg_binding_domain", "cage", "race", "size_fractionation", "padlock_probes_capture", "inverse_rrna", "oligo_dt", "polya", "repeat_fractionation", "unspecified", "other")
- `layouts` (array, nullable) — Filter by whether reads are paired-end or single-end (any-of) (one of: "paired", "single")
- `access` (array, nullable) — Filter by whether the reads themselves are openly downloadable or require dbGaP authorisation (any-of) (one of: "public", "controlled")
- `mindate` (string, nullable) — Start of the date range (YYYY, YYYY/MM or YYYY/MM/DD); used with maxdate (examples: "2024")
- `maxdate` (string, nullable) — End of the date range (YYYY, YYYY/MM or YYYY/MM/DD); used with mindate (examples: "2024")
- `datetype` (string) — Which date the range applies to (default: "pdat"; one of: "pdat", "mdat")

## Response

### 200 — Successful Response

- `@type` (string) (default: "SraExperiment")
- `id` (string, required)
- `accession` (string) (default: "")
- `experiment_title` (string) (default: "")
- `name` (string) (default: "")
- `version` (string) (default: "")
- `status` (string) (default: "")
- `platform` (string) (default: "")
- `instrument_model` (string) (default: "")
- `run_count` (integer, nullable)
- `spot_count` (integer, nullable)
- `base_count` (integer, nullable)
- `size` (integer, nullable)
- `cluster_name` (string) (default: "")
- `is_load_done` (boolean) (default: false)
- `has_static_data` (boolean) (default: false)
- `has_filtered_data` (boolean) (default: false)
- `submitter_accession` (string) (default: "")
- `center_name` (string) (default: "")
- `contact_name` (string) (default: "")
- `lab_name` (string) (default: "")
- `study_accession` (string) (default: "")
- `study_title` (string) (default: "")
- `sample_accession` (string) (default: "")
- `sample_name` (string) (default: "")
- `organism` (string) (default: "")
- `common_name` (string) (default: "")
- `taxid` (string) (default: "")
- `bioproject_accession` (string) (default: "")
- `biosample_accession` (string) (default: "")
- `library_name` (string) (default: "")
- `library_strategy` (string) (default: "")
- `library_source` (string) (default: "")
- `library_selection` (string) (default: "")
- `library_layout` (string) (default: "")
- `library_construction_protocol` (string) (default: "")
- `nominal_length` (integer, nullable)
- `nominal_sdev` (number, nullable)
- `controlled_access_study` (string) (default: "")
- `controlled_access_consent` (string) (default: "")
- `runs` (array) (default: [])
  - `@type` (string) (default: "SraRun")
  - `accession` (string, required)
  - `spot_count` (integer, nullable)
  - `base_count` (integer, nullable)
  - `cluster_name` (string) (default: "")
  - `is_public` (boolean) (default: false)
  - `is_load_done` (boolean) (default: false)
  - `is_unavailable` (boolean) (default: false)
  - `has_static_data` (boolean) (default: false)
  - `has_filtered_data` (boolean) (default: false)
  - `url` (string) (default: "")
- `created_date` (string) (default: "")
- `updated_date` (string) (default: "")
- `url` (string) (default: "")

## Errors

### 422 — Validation Error

The request body did not validate

What to do: Check the fields against this schema. A URN with the wrong prefix is the most common cause.

- `detail` (array)
  - `loc` (array, required)
  - `msg` (string, required)
  - `type` (string, required)
  - `input` (any)
  - `ctx` (object)

### 408

The request ran past its time limit

What to do: Raise `timeout` in the request body, up to the maximum this endpoint documents. Lowering `count` or turning off the `with_*` flags also helps, because less work finishes sooner.

### 412

The entity was not found, or a precondition failed

What to do: Retrying will not help: either the entity does not exist, or the input points at a different one.

### 429

Too many requests: a rate limit or a usage window is exhausted

What to do: When the response carries an X-Retry-After header, wait that many seconds and retry: the same number is in the body as `detail.retry_after`, and the limit clears once that window passes. The message in the body names the limit that was hit.

### 500

Something broke on our side

What to do: Retrying will not help. If it keeps happening, send us the X-Request-ID from the response headers.

### 529

Rate limit reached, or the endpoint is overloaded

What to do: Wait at least 30 seconds, then retry.

## Response envelope

Success: Array of objects (may be empty if no results)

Error: Error may coexist with partial results if it occurs mid-execution. Check X-Error header and status code.

Every response carries these headers:

- `X-Error` — Error message text (present only on error)
- `X-Request-ID` — Unique request identifier
- `X-Execution-Time` — Execution time in seconds
- `X-Result-Count` — How many records the body carries. 0 means an empty result, which is a normal answer and not by itself an error. A non-zero count can come back together with X-Error when the failure happened partway through — read this header and X-Error independently.
- `X-Total-Available-Results` — How many records exist for this query, when the endpoint can say. On a `dry_run` request this is the answer and the body is empty. It saturates: the endpoint's documented maximum means 'at least that many', any smaller number is exact.
- `X-Warning` — Present when the request body carried keys this endpoint does not document. They were ignored, so any filter you meant to apply through them did not apply. Check the spelling against this schema and retry.
- `X-Retry-After` — Seconds to wait before retrying. Present only on 429.