Find alternate parts

One call returns the parts that could replace a part, and what is on the shelf for each of them. Use it when a part is short, end-of-life or single-sourced. Research a part carries the same list in its alternates field; this call returns it without the rest of the report.

The call

import os

import requests

response = requests.get(
    "https://api.partfinder.dev/v1/alternates",
    headers={"Authorization": f"Bearer {os.environ['PARTFINDER_API_KEY']}"},
    params={"mpn": "TPS54331DR"},
)
print(response.json())

const response = await fetch("https://api.partfinder.dev/v1/alternates?mpn=TPS54331DR", {
  headers: { Authorization: `Bearer ${process.env.PARTFINDER_API_KEY}` },
});
console.log(await response.json());

curl "https://api.partfinder.dev/v1/alternates?mpn=TPS54331DR" \
  -H "Authorization: Bearer $PARTFINDER_API_KEY"

mpn is the only required parameter. Pass manufacturer only for a part number several manufacturers make, such as NE555N.

The first call for a part can take several seconds; repeat calls are faster. Stock is current on every call.

What comes back

{
  "as_of": "2026-09-29T07:28:59.267Z",
  "summary": "3 alternates for TPS54331DR: AP63301WU-7 (Diodes Incorporated), AP63300WU-7 (Diodes Incorporated), AP64351SP-13 (Diodes Incorporated). 3 of them are in stock at a distributor. Confirm fit against the datasheets before substituting.",
  "notice": "Informational only. ...",
  "part": { "mpn": "TPS54331DR", "manufacturer": null },
  "alternates": [
    {
      "mpn": "AP63301WU-7",
      "manufacturer": "Diodes Incorporated",
      "description": "Adjustable 3 A step-down regulator, 6-pin package",
      "match": "similar",
      "lifecycle": "Active",
      "supply": {
        "stock": { "value": 81702, "unit": "units" },
        "distributor_count": 3,
        "lead_time_median": { "value": 101, "unit": "days" }
      }
    }
  ]
}

Shortened to one alternate. The full field reference is the “Find alternate parts” page in the API Reference tab, generated from our OpenAPI document.

summary is one sentence you can relay as it is.
alternates holds up to five parts. It never includes the part you asked about, or the same part in another package or ordering variant. It is not ranked: compare the entries on match, supply and the datasheets, not on their position. An empty list means none was found; that is an answer, not an error.
match is how a supplier catalogue classifies the alternate against your part: direct, parametric_equivalent, similar or upgrade. It is null when there is no classification.
lifecycle is where the alternate is in its life (Active, NRND, EOL and so on).
supply is what distributors hold now; distributor_count counts distributors holding stock. A figure we could not read is null with a reason, never a zero.

An alternate is a candidate, not a qualification. Confirm pinout, package and electrical specifications against both datasheets before substituting.

There is no compatibility score

This endpoint does not rate how well an alternate fits, how risky it is, or what it costs relative to your part. We only publish what we can back with data, and for an alternate that is what it is, how a catalogue classifies it, and what is on the shelf. For the full risk picture of an alternate, call Research a part with its part number.

When the part number is wrong

The same checks as Research a part run first, with the same errors (404 part_not_found, 422 not_a_specific_part, 503 verification_unavailable); did_you_mean carries real part numbers to retry with when there are any. Every code is on the Errors page.

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The call

What comes back

There is no compatibility score

When the part number is wrong

​The call

​What comes back

​There is no compatibility score

​When the part number is wrong

The call

What comes back

There is no compatibility score

When the part number is wrong